[natedog7700]

Ive been runnning the MHD flash for 2 months so far with no problems, wedge tuned. My engine light came on the other day . Showed 4 codes (in description below). From my understanding, the MHD covers up the engine light for the cats, but why does it keep coming back? I replaced a clamp that was giving me a bad boost leak and replaced parts on my bumper after hitting a raccon. So when I took the car off the stands after a few days, I got these codes. coincidence? Seems irrelevant to replace a few things not related to the engine and get these codes. Took it out for a spin and it drove fine, ran fine. Then I got a misfire and had to restart the car doing a WOT pull. Ever since then i did a few pulls and everything seemed OK. Although my logs dont look to good at all. what do you guys think?

http://datazap.me/u/natedog7700/2015...og=0&data=4-21

Picture files are too big but the codes im getting are
2C9C - Front of cat signal
2C9D - Front cat 2 signal
2C9E - Heating behind cat input signal
2C9f - Heating behind cat 2 input signal

29D1 - Cylinder 5 Misfire
29D0 - Cylinder 4 misfire
29CC - multiple cylinder misfire

[ferocity02]

Your AFR and fuel trims are flatlined.

MHD will hide cat inefficiency codes for DP's. These codes seem to indicate that your sensors aren't working at all. The logs seem to show this as well.

Did you do anything to the sensors? Any other mods or maintenance? Forget to plug something in? Check for melted wires maybe. Although it does seem a bit odd for all four sensors to go at once.

I would not drive it until it's fixed. Without O2 sensor feedback it could be running wildly lean or rich.

[natedog7700]

Originally Posted by ferocity02

Your AFR and fuel trims are flatlined.

MHD will hide cat inefficiency codes for DP's. These codes seem to indicate that your sensors aren't working at all. The logs seem to show this as well.

Did you do anything to the sensors? Any other mods or maintenance? Forget to plug something in? Check for melted wires maybe. Although it does seem a bit odd for all four sensors to go at once.

I would not drive it until it's fixed. Without O2 sensor feedback it could be running wildly lean or rich.

I hit a raccon the other day. Had it on jack stands for a few days to replace the mesh on the front bumper. Fixed an intercooler clamp that was causing a boost leak. Took it off the stands and started it up to see the enging light on . But all seems irrelevant to the sensors going out. So your saying ALL 4 sensors are out? The car idles and drives fine though. How could this be? Electrical issue or sensor issue? Something other than the 02 Sensors causing the problem?

[Julian2485]

Originally Posted by natedog7700

I hit a raccon the other day. Had it on jack stands for a few days to replace the mesh on the front bumper. Fixed an intercooler clamp that was causing a boost leak. Took it off the stands and started it up to see the enging light on . But all seems irrelevant to the sensors going out. So you saying ALL 4 sensors are out? The car idles and drives fine though. How could this be? Electrical issue or sensor issue? Something other than the 02 Sensors causing the problem?

Check your O2 sensors, see if the wires are cut or anything

[ferocity02]

I agree, seems unlikely that all four sensors would go out, but your log confirms what the codes are saying. Try also logging bank 2 lambda. If you have INPA you can run diagnostics on the O2 sensors.

Also try flashing back to stock, maybe it's a software issue, again unlikely since it's been fine for 2 months. But its part of the troubleshooting process.

[natedog7700]

Originally Posted by Julian2485

Check your O2 sensors, see if the wires are cut or anything

Got the car on stands right now. I'll let you guys know what I find!

[natedog7700]

Originally Posted by ferocity02

I agree, seems unlikely that all four sensors would go out, but your log confirms what the codes are saying. Try also logging bank 2 lambda. If you have INPA you can run diagnostics on the O2 sensors.

Also try flashing back to stock, maybe it's a software issue, again unlikely since it's been fine for 2 months. But its part of the troubleshooting process.

Post cat, grey sheath 02 sensor got crimped. My mistake for rushing things on maintenance work. Should have checked before asking lol. Thanks guys!

[ferocity02]

I wonder why it was causing all 4 sensors to not read? Maybe the sensors all share a common reference voltage circuit, so grounding one would cause all of them to be grounded.

Glad you found the issue!

[Mike@N54Tuning.com]

Glad you found the issue.

Mike