Check Engine Light
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
Check Engine Light
Okay, this is weird. (Car is new to me with 1300 mi, delivered last Tuesday) Last Friday, I went for the Colorado Emissions Test, and when I pulled in, the Check Engine Light was NOT on. When they pulled it out, it was on. I immediately went back to the mgr and said "Hey what did you do?" She said the light was on when I gave the car to her. NO, it wasn't, but I can't prove it.
So, I've meanwhile learned that a steady light means there's an emissions system problem, and they should not have passed the car with that light on. So, she was obviously lying, or it came on right when I started it back up after the test. SO, I came home, read everything I could, checked the fuel cap, and today I put a full tank of 91 octane in it and drove about 30 miles, and it's still on. The manual said this can come on after changing gas and can take a couple of tanks to clear. Well, I think it's most likely old gas from being stored so long. The previous owner hadn't even licensed the car since July of 2010, so God only knows how old that gas is, and I don't know if he put Sta-Bil in it, either. Before I hook up to a code reader and clear it, anyone have any experience or thoughts about this? Thanks!
Best regards,
...z
So, I've meanwhile learned that a steady light means there's an emissions system problem, and they should not have passed the car with that light on. So, she was obviously lying, or it came on right when I started it back up after the test. SO, I came home, read everything I could, checked the fuel cap, and today I put a full tank of 91 octane in it and drove about 30 miles, and it's still on. The manual said this can come on after changing gas and can take a couple of tanks to clear. Well, I think it's most likely old gas from being stored so long. The previous owner hadn't even licensed the car since July of 2010, so God only knows how old that gas is, and I don't know if he put Sta-Bil in it, either. Before I hook up to a code reader and clear it, anyone have any experience or thoughts about this? Thanks!
Best regards,
...z
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
Best regards,
...z
Last edited by ZeekDuff; Jul 18, 2011 at 02:20 PM.
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
Courtesy of Bill Curlee... Make sure you read the WHOLE THING if you've never pulled your codes before. It's really not that long...
POST DTCS!!!
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
READING YOUR Engine Diagnostic Trouble Codes (DTC)
This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.
Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.
If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.
NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.
These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs
Here are some very good sites that explain what DTC mean:
http://www.gearchatter.com/viewtopic11755.php
http://www.obd-codes.com/trouble_cod...d-ii-codes.php
Make sure to include the H or C suffix when you post your DTCs!!
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Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
Thanks to everyone, one more time!
Best regards,
...z
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
The codes...
Okay gents, I have the codes after a brief bout with the family's genetic learning disability, "Dufflexia." Took me a minute to get that I could step through 'em and not try to write 7,000 WPM... Anyway:
Only one with a 'C'
10-PCM P0410 H C
all the rest are 'H' only - if there are only 2 digits, the previous letter & 2 digits apply to the beginning of those 2 showing:
4codes:
20-RCS C1221 H
22
48
78
5 codes:
AO-LDCM B2252 H
82
86
84
4 codes:
A1-RDCM B2283 H
87
85
U1064 H
1 code:
A6-SCM B0851 H
and 1 code:
BO-RFA U1255 H
That's it, everything else was "no codes." I reset them all manually, and started the engine and the Check Engine light was gone, I have not driven it yet, I was in my um, "lounge" or not fit for public viewing clothes...
So, wha' hoppend, please? 
Best regards,
...z
"Everything that can be invented, has been invented."
-Charles H. Duell, US Commissioner of Patents, in 1899
Only one with a 'C'
10-PCM P0410 H C
all the rest are 'H' only - if there are only 2 digits, the previous letter & 2 digits apply to the beginning of those 2 showing:
4codes:
20-RCS C1221 H
22
48
78
5 codes:
AO-LDCM B2252 H
82
86
84
4 codes:
A1-RDCM B2283 H
87
85
U1064 H
1 code:
A6-SCM B0851 H
and 1 code:
BO-RFA U1255 H
That's it, everything else was "no codes." I reset them all manually, and started the engine and the Check Engine light was gone, I have not driven it yet, I was in my um, "lounge" or not fit for public viewing clothes...
So, wha' hoppend, please? Best regards,
...z
"Everything that can be invented, has been invented."
-Charles H. Duell, US Commissioner of Patents, in 1899
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
NOW, is it possible as someone suggested yesterday, that taking off the gas cap while the engine is running could cause the light to come on? I think it was running when the guy pulled the cap, 'cause he figured he had to have the key on to open the filler door (I think he also went to ask someone or look up how to open the door), then he got out to look to be sure the door was open, then went to get his tester & finally shut it off right before doing the test, so the cap was off for maybe a minute or 2 with the engine running. But, even if so, why throw that particular AIR code? The gas cap shouldn't have anything to do with the AIR system, should it?
After reading many of the threads on this topic, it appears my car doesn't even have enough miles on it to have that particular pump/elc mtr malfunction. The car hadn't been driven by the previous owner since well before July of 2010, until he was ready to sell it just a month or so ago. I had driven it about 15 miles before the test that day, going to the facility (max speed 50 MPH), and returning home for a new pad of checks, then back to the facility. I had driven it maybe 4 miles after unloading it from the carrier, just home delivery day, 'cause it was Longmont's version of "Rush Hour," then immediately downtown to the license place the next day ('cause of the expired MN plate), then home again to await the seller sending me the Release Of Lien before I could do anything else to get the title transferred, do the emissions test, get plates. Now all done, about 40 miles total driving since receiving it. (MAN, it's fun to drive this Blue Beasty!!!)
SO, I'm still suspicious of the testing facility, I know dang well they should NOT have passed the car if that light was on, yet the young female manager insisted it was on when she looked at the odometer before turning it over to a tester to drive it inside. I believe perhaps she did start the engine to look at it, but don't recall for sure. If she just turned the key on without starting it, OF COURSE the light was on.
However, in ANY case, wouldn't you think they'd stop right there when she (if she) saw that light and instead of testing it anyway, told me to go get it looked at for that light being on? Makes no damned sense. If she didn't see the light, then she lied to me. If it was on, why didn't the tester see it and stop the test immediately? I suppose it's "possible" the light came on immediately upon exiting the lane, but then why continue with the gas cap test, why do the computer print-out with a stellar passing grade (VERY clean running car!) with that light still on, and not even mentioning it to me, my then going back inside after driving maybe 10' and MY seeing that light, to ask what the heck they did to my brand new car? Again, this car has 1300 miles on it. Was that list of H codes excessive for so few miles?
The only reason I'm pressing the issue is one thing or another wrong occurred at the testing facility; either the manager lied about seeing the light and should be reprimanded; or she didn't lie and the car should have IMMEDIATELY failed the test and she should be reprimanded; or they did something odd to make the car throw the code (like bumping some part of the AIR system?), and now it's resolved, but the higher-ups should still be warned about sloppy management at this facility. In any case, I want to report all this to whomever is in charge of the emissions testing in Colorado, because somebody over there screwed up royally, if it was a pure coincidence, and the car threw the code AFTER the test, even then, I was just plain lied to.
Thanks guys, at least I know as my gut had told me, it's nothing serious. Great ol' forum comes through for me once again!!!
Best regards,
...z
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
On my 2nd car, a dark metallic green 1952 Mercury 2dr hardtop (very sharp car, & quick for it's day), the kingpins were bad, one really loose. I replaced all the bushings myself, put in new zerks, and it looked like the really bad one had never had grease due to a clogged zerk for the top bushing. And, that test probably saved my life.
These emissions tests are just a way for political cronies to make money, IMO.
Best regards,
...z
Last edited by ZeekDuff; Jul 19, 2011 at 05:54 PM.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Yes, if you open the fuel tank while its running, it should set a code which would most likely turn on the CEL. I'm not positive but there are checks for it in the computer.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I cleared them ALL when I was done writing them down. I didn't rerun them after I'd started it earlier, not until just now; I started the car again, ran it for a few minutes, shut it off, ran the codes check again, and no codes. No Check Engine light anymore, either.
NOW, is it possible as someone suggested yesterday, that taking off the gas cap while the engine is running could cause the light to come on? I think it was running when the guy pulled the cap, 'cause he figured he had to have the key on to open the filler door (I think he also went to ask someone or look up how to open the door), then he got out to look to be sure the door was open, then went to get his tester & finally shut it off right before doing the test, so the cap was off for maybe a minute or 2 with the engine running. But, even if so, why throw that particular AIR code? The gas cap shouldn't have anything to do with the AIR system, should it?
After reading many of the threads on this topic, it appears my car doesn't even have enough miles on it to have that particular pump/elc mtr malfunction. The car hadn't been driven by the previous owner since well before July of 2010, until he was ready to sell it just a month or so ago. I had driven it about 15 miles before the test that day, going to the facility (max speed 50 MPH), and returning home for a new pad of checks, then back to the facility. I had driven it maybe 4 miles after unloading it from the carrier, just home delivery day, 'cause it was Longmont's version of "Rush Hour," then immediately downtown to the license place the next day ('cause of the expired MN plate), then home again to await the seller sending me the Release Of Lien before I could do anything else to get the title transferred, do the emissions test, get plates. Now all done, about 40 miles total driving since receiving it. (MAN, it's fun to drive this Blue Beasty!!!)
SO, I'm still suspicious of the testing facility, I know dang well they should NOT have passed the car if that light was on, yet the young female manager insisted it was on when she looked at the odometer before turning it over to a tester to drive it inside. I believe perhaps she did start the engine to look at it, but don't recall for sure. If she just turned the key on without starting it, OF COURSE the light was on.
However, in ANY case, wouldn't you think they'd stop right there when she (if she) saw that light and instead of testing it anyway, told me to go get it looked at for that light being on? Makes no damned sense. If she didn't see the light, then she lied to me. If it was on, why didn't the tester see it and stop the test immediately? I suppose it's "possible" the light came on immediately upon exiting the lane, but then why continue with the gas cap test, why do the computer print-out with a stellar passing grade (VERY clean running car!) with that light still on, and not even mentioning it to me, my then going back inside after driving maybe 10' and MY seeing that light, to ask what the heck they did to my brand new car? Again, this car has 1300 miles on it. Was that list of H codes excessive for so few miles?
The only reason I'm pressing the issue is one thing or another wrong occurred at the testing facility; either the manager lied about seeing the light and should be reprimanded; or she didn't lie and the car should have IMMEDIATELY failed the test and she should be reprimanded; or they did something odd to make the car throw the code (like bumping some part of the AIR system?), and now it's resolved, but the higher-ups should still be warned about sloppy management at this facility. In any case, I want to report all this to whomever is in charge of the emissions testing in Colorado, because somebody over there screwed up royally, if it was a pure coincidence, and the car threw the code AFTER the test, even then, I was just plain lied to.
Thanks guys, at least I know as my gut had told me, it's nothing serious. Great ol' forum comes through for me once again!!!
Best regards,
...z
NOW, is it possible as someone suggested yesterday, that taking off the gas cap while the engine is running could cause the light to come on? I think it was running when the guy pulled the cap, 'cause he figured he had to have the key on to open the filler door (I think he also went to ask someone or look up how to open the door), then he got out to look to be sure the door was open, then went to get his tester & finally shut it off right before doing the test, so the cap was off for maybe a minute or 2 with the engine running. But, even if so, why throw that particular AIR code? The gas cap shouldn't have anything to do with the AIR system, should it?
After reading many of the threads on this topic, it appears my car doesn't even have enough miles on it to have that particular pump/elc mtr malfunction. The car hadn't been driven by the previous owner since well before July of 2010, until he was ready to sell it just a month or so ago. I had driven it about 15 miles before the test that day, going to the facility (max speed 50 MPH), and returning home for a new pad of checks, then back to the facility. I had driven it maybe 4 miles after unloading it from the carrier, just home delivery day, 'cause it was Longmont's version of "Rush Hour," then immediately downtown to the license place the next day ('cause of the expired MN plate), then home again to await the seller sending me the Release Of Lien before I could do anything else to get the title transferred, do the emissions test, get plates. Now all done, about 40 miles total driving since receiving it. (MAN, it's fun to drive this Blue Beasty!!!)
SO, I'm still suspicious of the testing facility, I know dang well they should NOT have passed the car if that light was on, yet the young female manager insisted it was on when she looked at the odometer before turning it over to a tester to drive it inside. I believe perhaps she did start the engine to look at it, but don't recall for sure. If she just turned the key on without starting it, OF COURSE the light was on.
However, in ANY case, wouldn't you think they'd stop right there when she (if she) saw that light and instead of testing it anyway, told me to go get it looked at for that light being on? Makes no damned sense. If she didn't see the light, then she lied to me. If it was on, why didn't the tester see it and stop the test immediately? I suppose it's "possible" the light came on immediately upon exiting the lane, but then why continue with the gas cap test, why do the computer print-out with a stellar passing grade (VERY clean running car!) with that light still on, and not even mentioning it to me, my then going back inside after driving maybe 10' and MY seeing that light, to ask what the heck they did to my brand new car? Again, this car has 1300 miles on it. Was that list of H codes excessive for so few miles?
The only reason I'm pressing the issue is one thing or another wrong occurred at the testing facility; either the manager lied about seeing the light and should be reprimanded; or she didn't lie and the car should have IMMEDIATELY failed the test and she should be reprimanded; or they did something odd to make the car throw the code (like bumping some part of the AIR system?), and now it's resolved, but the higher-ups should still be warned about sloppy management at this facility. In any case, I want to report all this to whomever is in charge of the emissions testing in Colorado, because somebody over there screwed up royally, if it was a pure coincidence, and the car threw the code AFTER the test, even then, I was just plain lied to.
Thanks guys, at least I know as my gut had told me, it's nothing serious. Great ol' forum comes through for me once again!!!
Best regards,
...z
Take her for a drive and ENJOY the rest of your day.. MANY,,,, MANY,,, MANY things cause spurious DTCs. Unless they have a "C" meaning CURRENT,, there just indicators of things that have happened and now are not happening.
Don't get me wrong,, history DTCs tell a story. Unless, you intent is to whip on the Emissions Operator,, half of them don't know much about anything more than Honda's If it were me,, Ide just chalk it up to Sh%4 happens.
Bill
Thread Starter
Racer
Joined: Feb 2011
Posts: 374
Likes: 4
From: Longmont CO
Ya know,,,,, ALL THAT SAID,,,,,,,,,,,,,, just clear the DTCs and if they don't come back,,,,, Take her for a drive and ENJOY the rest of your day..
MANY,,,, MANY,,, MANY things cause spurious DTCs. Unless they have a "C" meaning CURRENT,, there just indicators of things that have happened and now are not happening.
Don't get me wrong,, history DTCs tell a story. Unless, you intent is to whip on the Emissions Operator,, half of them don't know much about anything more than Honda's If it were me,, Ide just chalk it up to Sh%4 happens.
Bill
Take her for a drive and ENJOY the rest of your day.. MANY,,,, MANY,,, MANY things cause spurious DTCs. Unless they have a "C" meaning CURRENT,, there just indicators of things that have happened and now are not happening.
Don't get me wrong,, history DTCs tell a story. Unless, you intent is to whip on the Emissions Operator,, half of them don't know much about anything more than Honda's If it were me,, Ide just chalk it up to Sh%4 happens.
Bill
Best regards,
...z
