check engine light
Thread Starter
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Joined: Mar 2009
Posts: 54
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From: New Orleans LA
check engine light
Last night I took my 91 coup out for a drive after radiator replacement.
After 15 min. the check engine light came on. It had done this once prior to the radiator replacement. That's when we found the crack.
After returning to the garage, no problems with leaks. Oil pressure, engine temp etc was all good. Just the darn "check engine" light came on.
So I unhooked the battery and went to this forum. I learned some about sensors MAF and MAT. Since I had disconnected the battery, the ECM codes had been reset and there was nothing showing up when I tried to recover the error codes.
So, I tried again this morning. I got a fresh tank of gas as I was running low. I ran it and ran it and no codes. So here's my question.
My car has been being worked on (new paint etc). It has had the same tank of gas in it for the past 3-4 months. Could old gasoline have caused the sensors to read something strange and given me the "check engine" light reading?
Let me know what you guys think. I'm just looking to learn
1991 coup, if you need that info.
And thanks.
After 15 min. the check engine light came on. It had done this once prior to the radiator replacement. That's when we found the crack.
After returning to the garage, no problems with leaks. Oil pressure, engine temp etc was all good. Just the darn "check engine" light came on.
So I unhooked the battery and went to this forum. I learned some about sensors MAF and MAT. Since I had disconnected the battery, the ECM codes had been reset and there was nothing showing up when I tried to recover the error codes.
So, I tried again this morning. I got a fresh tank of gas as I was running low. I ran it and ran it and no codes. So here's my question.
My car has been being worked on (new paint etc). It has had the same tank of gas in it for the past 3-4 months. Could old gasoline have caused the sensors to read something strange and given me the "check engine" light reading?
Let me know what you guys think. I'm just looking to learn
1991 coup, if you need that info.
And thanks.
Safety Car
Joined: Jan 2008
Posts: 3,939
Likes: 1
From: Vero Beach Florida
Here are the 85 - 91 codes
If it comes back read the code before you clear it. When you tried to read it you should have gotten a 12
1985-1991: ECM Codes
Code #12: Normal No Codes.
Code #13: Open Oxygen Sensor Circuit.
Code #14: Coolant Sensor Circuit Low.
Code #15: Coolant Sensor Circuit High.
Code #21: Throttle Position Sensor High.
Code #22: Throttle Position Sensor Low.
Code #23: Manifold Air Temperature Circuit High.
Code #24: Vehicle Speed Sensor.
Code #25: Manifold Air Temperature Circuit Low.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Code #36: Mass Air Flow Sensor Burn-Off Function Fault.
Code #41: Cylinder Select Error.
Code #42: Electronic Spark Timing.
Code #43: Electronic Spark Control.
Code #44: Lean Exhaust indication.
Code #45: Rich Exhaust Indication.
Code #46: Vehicle Anti Theft Fault.
Code #51: Faulty Mem-Cal.
Code #52: Fuel Calpak Missing.
Code #52: (1990-91 Corvette Only): Engine Oil Temperature Sensor Low.
Code #53: System Over Voltage.
Code #54: Fuel Pump Circuit Low Voltage.
Code #55: Defective ECM.
Code #62: Engine Oil Temperature Sensor Circuit High.
If it comes back read the code before you clear it. When you tried to read it you should have gotten a 12
1985-1991: ECM Codes
Code #12: Normal No Codes.
Code #13: Open Oxygen Sensor Circuit.
Code #14: Coolant Sensor Circuit Low.
Code #15: Coolant Sensor Circuit High.
Code #21: Throttle Position Sensor High.
Code #22: Throttle Position Sensor Low.
Code #23: Manifold Air Temperature Circuit High.
Code #24: Vehicle Speed Sensor.
Code #25: Manifold Air Temperature Circuit Low.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Code #36: Mass Air Flow Sensor Burn-Off Function Fault.
Code #41: Cylinder Select Error.
Code #42: Electronic Spark Timing.
Code #43: Electronic Spark Control.
Code #44: Lean Exhaust indication.
Code #45: Rich Exhaust Indication.
Code #46: Vehicle Anti Theft Fault.
Code #51: Faulty Mem-Cal.
Code #52: Fuel Calpak Missing.
Code #52: (1990-91 Corvette Only): Engine Oil Temperature Sensor Low.
Code #53: System Over Voltage.
Code #54: Fuel Pump Circuit Low Voltage.
Code #55: Defective ECM.
Code #62: Engine Oil Temperature Sensor Circuit High.
Thread Starter
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Joined: Mar 2009
Posts: 54
Likes: 0
From: New Orleans LA
engine light
Thanks for the codes. I found them last night while researching the check engine light on this forum. And of course that code 12 is all that I got.
Unfortunately I reset the thing unknowingly prior to doing my research. BUt I will certainly check the thing prior to resetting next time it happens.
Just for curiousity sake though, does anyone know if old gas might set off the sensor (MAF) or any other sensor to give this sort of Check Engine Light error? Just wondering.
Thanks.
Unfortunately I reset the thing unknowingly prior to doing my research. BUt I will certainly check the thing prior to resetting next time it happens.
Just for curiousity sake though, does anyone know if old gas might set off the sensor (MAF) or any other sensor to give this sort of Check Engine Light error? Just wondering.
Thanks.
Melting Slicks
Joined: Feb 2008
Posts: 3,286
Likes: 6
From: Palm Beach
Thread Starter
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Joined: Mar 2009
Posts: 54
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From: New Orleans LA
Ran great
I had it on the interstate and was punching the accelerator pedal. I kept going from 35 to 90 every so often to get the rpm's up . . . maybe blow out some carbon. Temp, oil, pressure . . . . . all the gauges were normal. I don't believe the engine temp got high enough to open the thermostat. Seems that only happens when the car is in traffic.
Anyway, I saw that dirty MAF sensors could cause the problem and figured why not old gasoline. I don't know. I'll keep looking for the light to go on and will do the on board computer code thing.
Thanks for the input.
Anyway, I saw that dirty MAF sensors could cause the problem and figured why not old gasoline. I don't know. I'll keep looking for the light to go on and will do the on board computer code thing.
Thanks for the input.
Safety Car
Joined: Jan 2008
Posts: 3,939
Likes: 1
From: Vero Beach Florida
NO 96 are different you have a OBDll I believe and you have many more codes then are used in the L98 you can check a lot more things. You really need a FSM. Try this link it will help explaine things
http://www.corvettebuyers.com/c4vettes/codes.htm
http://www.corvettebuyers.com/c4vettes/codes.htm
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Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
If your thermostat hasn't "opened up" and you were on the interstate, you have a problem with the thermostat. It is stuck open.
It should open up at least in about 10 minutes of driving, allowing the engine to go into closed loop. if the car didn't warm up, you might get a code 15, coolant sensor low.
you should monitor the temp, and if it stays below 150 and never gets to 195 in the summmer, you have a thermostat gone.
It should open up at least in about 10 minutes of driving, allowing the engine to go into closed loop. if the car didn't warm up, you might get a code 15, coolant sensor low.
you should monitor the temp, and if it stays below 150 and never gets to 195 in the summmer, you have a thermostat gone.
Last edited by coupeguy2001; Jul 21, 2009 at 07:35 AM.
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Joined: Mar 2009
Posts: 54
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From: New Orleans LA
not sure on that
I'm not too car savy. We just replaced the thermostat and the radiator.
When the car is sitting, the thermostat definitely opens. The fans kick on when the temp gets near 200 degrees or so. That's a guess cuz the dash gauge has no numbers other then high and low.
Once the fan kicks on, the temp goes down the way the system is supposed to work.
On the highway, with the noise of the road below and engine, all I can say is the temp. never gets high. Whether the thermostat opens up or not, I don't know. I assumed that it opens up when the temp gets above 190 degrees to let water from the radiator flow into the engine to cool it off.
Isn't that correct?
When the car is sitting, the thermostat definitely opens. The fans kick on when the temp gets near 200 degrees or so. That's a guess cuz the dash gauge has no numbers other then high and low.
Once the fan kicks on, the temp goes down the way the system is supposed to work.
On the highway, with the noise of the road below and engine, all I can say is the temp. never gets high. Whether the thermostat opens up or not, I don't know. I assumed that it opens up when the temp gets above 190 degrees to let water from the radiator flow into the engine to cool it off.
Isn't that correct?
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
The "91" L98 engine does not have a MAF sensor. The "91" uses a MAP sensor.
If the Check Engine Light displays again, just get the codes and go from there. Has the check engine light displayed recently?
If the Check Engine Light displays again, just get the codes and go from there. Has the check engine light displayed recently?
Last edited by GKK; Jul 21, 2009 at 10:31 AM.
Thread Starter
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Joined: Mar 2009
Posts: 54
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From: New Orleans LA
Nothing no problems
Ever since I had the fresh tank of gasoline in the tank, the light won't come back on. I have seen older posts that say the MAP or MAF sensors being dirty can cause the "check engine" light to go on. They go on to explain how to clean some sensors and to check for loose wires or connections. It certainly makes me suspicious that these darn things are super sensitive.
I was just wondering if gasoline which is 4 months old might be capable of displaying a check engine light. Fortunately, there has been no problem since that one episode. All I did differently was put a fresh tank of gas in. Unfortunately I had reset the thing before checking the on board diagnostics the night before when I got the check engine light error.
So, I guess I'll just enjoy my good fortune for the time it lasts.
I was just wondering if gasoline which is 4 months old might be capable of displaying a check engine light. Fortunately, there has been no problem since that one episode. All I did differently was put a fresh tank of gas in. Unfortunately I had reset the thing before checking the on board diagnostics the night before when I got the check engine light error.
So, I guess I'll just enjoy my good fortune for the time it lasts.
Instructor
Joined: Feb 2008
Posts: 177
Likes: 5
From: Toronto Ontario
I doubt that 4 month old gas could trigger an ECM code. In your case, your car only has a MAP sensor so you can rule out the MAF sensor. The MAP sensor reacts to barometric pressure and engine vacuum to help control the fuel mix and is not an item that gets contaminated with fuel or intake air.
