PCM: how long to re-learn after code reset?
 

Hi all,

I have a code P1416 from my PCM that brings up the check engine light occasionally. I know it's a minor stuck valve in the throttle body, but I have an emissions test coming up (yes, in the middle of winter, lovely:rolleyes:)and I don't want to screw with it.

So, I reset the code again tonight. Question is: how many miles/starts do I need to go (appoximately) before the PCM will pass emissions (assuming it does not re-light)? I went through this with my mother-in-law's Chrysler, and it took a lot longer than the emissions Nazi said (100 mi).

Best guess?

Thanks

You have to fix the problem before you can get the system to reset. Resetting the code isn't going to cause the malfunction to magically go away.

By the way this code doesn't have anything to do with the throttle body. You probably need to replace or clean the passenger side AIR check valve or fix a plumbing problem in the AIR pipes on that side. There are several threads on the forum with suggestions on how to solve the problem without pulling the check valve which is very difficult to get to.

Bill

Thanks, Bill. I know it won't fix anything but the way MD state law works, if the PCM is code free, it's a pass. But to read the PCM, it has to not have been re-set recently. It's at least 100 mi but I wonder how long for the Corvette PCM.

That depends on the drive cycles. All states have the same requirement on the reset of the codes. They have the requirement so you are forced to fix the problem. The shops usually say 100 miles from a reset because normally over that distance the car has cooled completely several times and has gone through the appropriate number of cold starts for everything to pass all of the tests and certify the emissions systems are OK. The code you see is related to starting the car. The PCM tells the air pump to inject air into the AIR pipes and monitors the O2 sensors to see if they indicate a lean condition. If they do then there is no problem. If the test fails two times in a row the MIL will be turned on. If you have a bad check valve on the passenger side and reset the code each time it shows up you will keep failing this test every second start no matter how many miles you drive. The only option is to fix the problem.

Bill

You better hope its real intermitted. The manual indicates:

A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

It is very intermittent! Soooo intermittent...the previous owner mentioned it AFTER he sold me the car as I was taking the keys & then I did not see it for about 1 year afterward. I get it more often than that now but it is still very infrequent. Thanks Sam & Bill! I'll do a search here on the fix if it comes back any time soon.

There is a driving cycle posted somewhere on this forum that can drastically reduce the time required to reset the computer after a battery disconnect or code clear.
Assuming of course the fault does not reset during this time.

I can't remember exactly what the title of the thread was; but you might search herein under things like "driving cycle", "computer reset", etc.

I did it, and it reset my computer to "all readiness tests complete" in less than 10 miles.
Something like:

Cold start at less than 176 degrees.
Warm engine.
Drive 5 miles at constant 55.
Coast down in gear to 20 MPH.
Accelerate modestly to 60 MPH
Drive 5 miles at 60.
Coast down to 20 again.
Accelerate briskly to 60 again.

To be sure, let the engine cool below 176, and do it all again.

DG

That's very, very helpful, Thanks!

It's the I/M monitors that go not ready when you reset the OBD codes. These monitors run ongoing tests on things link EVAP/Catalyst/EGR (on car equipeed with egrs) and several other systems. The do NOT illuminate the MIL lamp until they have failed several times. The standard OBD code lights the light for 2 consecutive errors in a time frame (different for different codes).

I don't think you can monitor the I/M monitors via the DIC, a cheapy OBD scanner will.

Just read this post,informative,and helpful,got me thinking,we are very fortunate 1, to have the internet 2,to have this forum 3,to actually have informed knowledgeable people answer our questions. Back in the day we usually had one guy that was pretty sharp and you had to kiss his a## now just a click and we have the cumulative knowledge and experience of countless mechanics ,tinker'ers and enthusiast's.Building cars today is probally more work the cars are more complex but simplified by the sharing of information Don't ever forget the Forum IS your friend

Do a search on P1416. You will find an old thread on "replacing the secondary check valve". This thread also discusses cleaning of the valve. Sometimes this works, sometimes it does not.

I cleaned mine by the process described in the mentioned thread. It lasted for over two weeks. On the thrird week, it failed again, just as I was planning to get my emissions test done.

Since I already had the parts, I changed both valves. P1416 is for the passenger's side and the valve is located behind the intake manifold.

You have a lot of work ahead of you if the cleaning doesn't work.

1. rollers? it'll pass

2. unless someone here works for the state dmv, the info won't be correct(most likely)

Huh???:crazy:

I amcertified to insrect in the state of Texas. The info given in this thread has been excellent.I dought you would pass on my equip. , the "ready" parameters would not allow it. You really need to fix it!!!!!! Get it off your back and stop worrying about it.

GM OBDII driving readiness cycle

http://www.obdii.com/drivecycle.html

I started the CHECK VALVE CLEANING trhead a while back. Yep,,sometimes it works just fine and for some it doesnt. Its worth a try. Worked fantastic for me. Cold damp weather sometimes the check valves to gum up and stick. Some Autozones have code readers that will tell you the same info. They can read the codes for free. You just need to make sure that the reader that theu use has that feature.

If you know some one with EFI Live, they can plug it in and monitor the readiness checks. I just purchased a ACTRON CP 9180 engine code reader and scanner. Its does a number of functions other than just reading DTC. It also will check readiness codes/flags.

"all readiness tests complete" DUHHHHHHH????
 

I am trying to reset my monitors. Had a repair. I failed smog because they were not reset. Are the monitors and the "all readiness tests complete"the same. How can I tell if they are reset for my smog test. I am in So Cal. :willy: