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ECM Code 13 Question

Tommy Almond

Well-known member
Joined
Jul 11, 2010
Messages
73
Location
Stanley, NC
Corvette
1981
Okay all you '81 owners, I am getting a Code 13 on the ECM check which is the Oxygen Sensor Circuit. The check engine light will come on for anywhere to 5 secs to 2 minutes and go off, does not lock in and stay lite. Pull codes and 13 comes up. Check engine light has come on for a while when sitting at red light as well as when cruising down highway at 55mph.

Is there a trick to checking out the system to see if it is the sensor itself or if it is too lean or rich at times?

I have all parts on the car, everything works and the car is as close to factory as I can keep her so no modifications done. It has a 350 GM crate motor, 195HP installed last summer and I am running 87 octane gas most of the time since timing is still set to factory spec and have no spark knock or other low octane tale tell signs. Also Q-jet carb was re-manufactured last winter by All American Carbs and have had no problems out of it since installing.

Was getting the Code 13 before engine swap and carb work done, just maybe not as much as I am now. On 15 miles run this morning in cool temps the light lite up 3 times. Does it whether in cool or hot weather.

Thanks in advance for thoughts or comments. Let's keep these '81s on the road.
 
If I remember correctly full lean or full rich will give you different codes (no code 13).
But if it was mine, the oxynen sensor needs to be replaced from time to time so this may be a good time to do so :)

Greetings Peter
 
Peter good catch there, I didn't see in the manual that at first but double checked after your post and yes if a lean reading that gives a 44 code and rich gives a 45. Thanks for that info to make me search deeper so probably is the O2 sensor itself and or the connection.
 
There are seperate codes for lean and rich. I attached the 13 trouble shooting tree from the service manual. For the cost of an oxygen sensor, I would just change it and see if the code clears itself. -- If not it is probably a wiring issue.
The light going on and off is OK -- It just means the problem is intermittent.

TroubleCode13.jpg
 
New O2 Sensor

Well installed a new O2 sensor, for $35 why not. Initial run was better improvement. Check Engine light only came on once for 3 to 4 seconds after I reset the ECM so will test run some more and see if the light stays off now....or at least less than before. Removed an AC Delco sensor and it was bad sooted so hope this helps.
 
Well installed a new O2 sensor, for $35 why not. Initial run was better improvement. Check Engine light only came on once for 3 to 4 seconds after I reset the ECM so will test run some more and see if the light stays off now....or at least less than before. Removed an AC Delco sensor and it was bad sooted so hope this helps.

So what is the code now? If the check engine light comes on, check the code. The ECM codes will help to find the problem.
 
New O2 Sensor The Charm

New O2 sensor in and ECM system doing just like out of factory and ar even runs better so maybe now ECM has stopped going in and out of closed loop. Best $35 spent this summer so far. Thanks to all for your help.
 

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