So I am trying to get rid of my check engine light and the computer codes are driving me crazy.

Originaly I was getting only p0140 which I had a mechanic look at and he told me it was something wrong with the 2nd sensor on the right side of the engine. About 2 years ago I installed an 02 sim on the first sensor. And today I installed an 02 sim on 2nd one. Now i have both connections connected to 02 sims. I cleared the computer with a simple scanner from autozone and drove the car for 15 miles and then the engine light went back on.

Now I am getting:

p0400 and p0140 (same code). How can I be getting p0140 with I already cleared it, and now p0400 which i think is a misfire.

Can anyone tell me what is wrong and what and how I should fix? I have no idea.

97 ss camaro. Thanks.

 

The P0140 code is for the LEFT side, not the right side. It is the downstream sensor. Some causes, besides a bad sensor, can be: exhaust leak, bad gas, backed out terminals, damaged connectors, or wiring problem.

The P0400 is an EGR problem. The valve could be bad, or just need a good cleaning. Could also be a problem with the connections.

If the car has headers, they could be contributing to both conditions.

 

http://www.obd-codes.com/p0400

http://www.obd-codes.com/p0140

 

You put an O2 sim on the "first sensor"...... as in the pre-cat sensor?

P0140 is for an "open circuit". That could be a harness problem, not necessarily a faulty sensor.

 

yeah injuneer, i put an 02 sim on the first one before the cat on the right side (passenger seat area) because I was getting error code(dont remember which) that indicated the CAT was bad. This was like 2 years ago. It was going to cost me an arm and a leg to replace the cat and I couldn't afford it. So now I have 2 02 sims on both sensors that are located on the passanger side of the engine.

And since the mechanic told me the other O2 sensor was bad the other day, i put it on that too. lol....I guess he is totally wrong. So it's the second on the left...Ugh..

I want to get this fixed the right way but I need to pass smog this week. Should i just swap the one i put on the right side and put it on the left? Will that get rid of the code for temporary?

As far as p0400, which is the egr aparrently, (i searched forums and was seeing that this code indicated a misfire). I am going to do a good seafoam to it this week. I hope that fixes it. But I bought an EGR valve a while ago but never got around to replacing it. Is it hard to replace? What tools would I need? It seems like a bitch to get to though since its behind the engine.

Thanks guys, appreciate all the help.

 

BTW, I hope i'm not confusing the right side and left side. By right side I mean as if you were sitting in the drivers seat and looking to the right side. The sensors I have 02 sims on are by where the passanger would be sitting. Are we on the same page?

 

car has no headers either, all stock.

 

O2 simulators are for the POST cat O2 sensors, NOT the pre-cat. The pre-cat O2 sensors are critical for fuel trim. Get rid of the O2 simm and put an AC Delco oxygen sensor in.

 

BINGO!!!

P0400 is for low flow through the EGR system, as measured by the PCM looking at the change in MAP when it cycles the EGR valve. You can get P0400 in OBD-II if you have a low back-pressure exhaust system. Check the pintle on the valve to make sure it isn't carboned up, check the vacuum line from the dirver's side of the intake manifold
to the EGR vacuum solenoid, and from the solenoid to the EGR valve. With the engine idling, push the EGR vavle open (or use a hand held vacuum pump to open it) and it should make the engine stumble. The vacuum pump test is the best way to do it.

 

shoot!!! Ok i will take that 02 sim off of the first one.

So just to be sure: is the p0140 code indicating that there is something wrong with the sensor that is under the car right behind passenger seat? or is it on the other side?

 

The P0140 is for the driver's side.

 

Bank 1 = left side = driver's side = cyls 1/3/5/7

Bank 2 = right side = passenger side = cyls 2/4/6/8

 

Thanks guys! I appreciate it. I'm going to try to tackle this problem tonight after work!

 

Sounds like adressing the catalytic converter and O2 sensor dyslexia is a great first step!

On an F-body, the front (pre-cat) O2 sensors use a flat plug and the rear (post-cat) sensors use a square plug.

 

hmm, really? When i put the 02 sim on the first one on the passenger side a while back it was the same connection as the back.

Oh yeah, can you guys tell me what tools do I need to get to replace the EGR valve? I see it sitting in the back of the engine. Is it just held on by 1 or 2 bolts? I'm gonna stop by autozone 2 nite to get whatever i need. THanks.