TSHong

Here you go Paul. Hope I'm not too late for you. I will also email you as well.

Pashamad

[QUOTE=MP4.2+6.0;24543835]

Stepping back from the codes though, that's a head scratcher. The carbon on the old sensor really suggests rich, not lean to me. Lean should be toward white, but certainly not sooted like that. So the visual doesn't agree w/ the lean code to me..[/QUOT

From my library - looks like there is leak in exhaust somewhere close to O2 sensor front - it shows lean, hence soot on rear sensor. Get under the car with fonendoscope and listen - it may be very small crack - BTDT. :-(
One more - compare voltages from all four front O2 sensors - should see the difference.

TSHong

If the ECM sees a lean condition then it tries to richens the fuel mixture. Sounds counter intuitive that a lean condition will cause you to run rich.

PaulW

Thanks for everyone's response. I was looking at pictures of when I did the transmission flush, and I can see the left hand side O2 sensor in the exhaust when it was disconnected, so it too is black and sooted.

Someone on QW suggested that I go under the car, disconnect the O2 sensor that I just installed, and then see what kind of codes I get. Make sure it's the same one (bank 1, post cat) that I have in my fault code. That's a good first step.

I will consider replacing the pre-cat sensor, as I know that is the "lean or rich" sensor that provides the feedback to the ECU. But for now I will continue to troubleshoot.

I'm not going to go through all the hassle to check if the O2 sensors are working at the plugs, I'm going to say they are (never say never, correct?) because if they were not, I would be getting other types of codes, not just a long term lean code.

I could never find a measuring block that shows the output voltage of the O2 sensors (as I recall).....if anybody knows what that is, I will take that and compare the readings to each other.

PaulW

[QUOTE=Pashamad;24543913]Pashamad: After looking through google, there is a lot of mentions of an exhaust leak associated with this code. When you say BTDT, does that mean you have had a similar code and found an exhaust leak? If so, where was it and what was the corrective action? Thanks!

Pashamad

Pashamad: After looking through google, there is a lot of mentions of an exhaust leak associated with this code. When you say BTDT, does that mean you have had a similar code and found an exhaust leak? If so, where was it and what was the corrective action? Thanks![/QUOTE]

Unfortunately, it's not one sentence talk, e-mail me privately for phone exchange - we'll talk about. (typing with one finger ;-)

TSHong

Hey Paul, looks like the requirements for the O2 test is that the heater for the O2 is good and no exhaust leak between the head and the cat. Obviously you would hear an exhaust leak but you never know.

I think you do have to check the precat O2 sensor as well.

halik

Again, if you're trying to trace fuel trim issues, only the precat O2 sensors matter. Post cat sensors only monitor cats, any issues there and you'll get a cat efficiency CEL, not fuel trim outside of range.

tx170754

a coincidence to the fact that you had recently the exaust removed ?

PaulW

The fault code has been around for 6-8 weeks before the exhaust was removed, it has nothing to do with it.