Check engine light
Thread Starter
5th Gear
Joined: Sep 2014
Posts: 5
Likes: 0
Check engine light
I have a 91 vette convertible, I just had the EGR valve and sensor replaced and I also had the O2 sensor replaced. On the way home from the shop the Check engine light came on again. I returned to the shop and the guy put the OGB1 tester on it at it read O2 sensor. Well since he just replaced that I don't know what it could be. Any Ideas.
Thank you Jack
Thank you Jack
Melting Slicks
Joined: Jan 2014
Posts: 2,192
Likes: 381
From: Lunenburg MA
Why were the EGR and O2 sensor replaced? What were they replaced with?
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Thread Starter
5th Gear
Joined: Sep 2014
Posts: 5
Likes: 0
Thank you I will have the shop check that out
Why were the EGR and O2 sensor replaced? What were they replaced with?
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The error code number might give us useful information, though it looks like 13 is the only O2 sensor error code. You could get that if the connector is not plugged in or the wire is shorted to ground.
Thread Starter
5th Gear
Joined: Sep 2014
Posts: 5
Likes: 0
Thread Starter
5th Gear
Joined: Sep 2014
Posts: 5
Likes: 0
Why were the EGR and O2 sensor replaced? What were they replaced with?
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Just "O2 sensor" isn't enough information to diagnose it. You probably need someone that can look at the O2 data stream in real time to see what it's doing. The error just tells you the signal was something unexpected at some point in time.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I had a similar situation with my 1985. Replaced the O2 with a new sensor and still 10-20 minutes driving and the check engine light would come back on. The 85 only has a single wire to the sensor. Drove me nuts. Finally was looking at a schematic for the ECM and is showed 2-3 wires over from the O2 sensor wire going into the ECM a ground wire for the O2 sensor. Didn't make much sense. I ended up running a ground wire to the block, cut and spliced into the wire to the ECM and that solved the problem. You could test this by running a temporary to the block with an alligator clip with the other end clipped to the wire to the ECM.
Remember this was an 85, I am not sure if your 91 would have the same ground wire to the ECM.
Remember this was an 85, I am not sure if your 91 would have the same ground wire to the ECM.
Thread Starter
5th Gear
Joined: Sep 2014
Posts: 5
Likes: 0
I had a similar situation with my 1985. Replaced the O2 with a new sensor and still 10-20 minutes driving and the check engine light would come back on. The 85 only has a single wire to the sensor. Drove me nuts. Finally was looking at a schematic for the ECM and is showed 2-3 wires over from the O2 sensor wire going into the ECM a ground wire for the O2 sensor. Didn't make much sense. I ended up running a ground wire to the block, cut and spliced into the wire to the ECM and that solved the problem. You could test this by running a temporary to the block with an alligator clip with the other end clipped to the wire to the ECM.
Remember this was an 85, I am not sure if your 91 would have the same ground wire to the ECM.
Remember this was an 85, I am not sure if your 91 would have the same ground wire to the ECM.
That just may be the problem. The thing I don't understand is why now. I have been driving this car for 10 yrs and never had this problem. I will check the ground Idea out. I don't think the ECM can be that different.
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Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I had driven my for about 5 years without an issue. I had the transmission rebuilt shortly before this happened and was thinking that perhaps the wire got pinched someplace.....but it is a ground. I believe my wire was orange...but could not find it in the engine compartment or under the car anywhere.