I have an 2002 EX, Sedan. The vehicle is stock with 110k miles on it. I have the car in the shop for a head gasket and radiator replacement. We did objectively verify the head gaket was bad. This acted up a year ago and I got 2 conflicting opinions on the issue so at that time the thermostat was replaced and the issue resolved itself (no heat). Fast forward to present day and the car is in the shop for the above stated work. 3 weeks later the work is done but the shop calls me to say the CEL is now on and the code is P0135. They troubleshoot it for 6 hours and a week later I get a call that the PCM which I think is really the ECM is bad. They say that the coollant contaminated the upstream O2 sensor which fried part of th PCM. I never got a CEL on my end, no overheat, etc. It was a very slow leak. Both O2 sensor were replaced with the correct parts in OCT 2017.

My question to the group is has anyone had this issue? Can the PCM get damaged from a contaminated O2 sensor? Shop says they can get me a refurbished PCM for $650 (installed) which includes having Honda reflash it. Tell me Honda won’t reflash a PCM out of a junked civic in a salvage yard. Any advise on causation and now an even more costly repair? Seems very coincidential that this all happened after the HG is replaced but nothing came up on my end before.

Thank you in advanve!

 

ECU's have been known to fry on this platform, and experiencing a failed headgasket is inconveniently common. Whether or not the O2 sensor caused the ECU to fail is debatable, but if you're having strange electrical issues in the car... it could be a likely culprit.

 

Thanks for the reply toyomatt84. Prior to dropping the car off at the shop I never experienced one electrical issue. When the shop called me to say the CEL was now on and spitting a code they said the first thing they did was to replace the upstream o2 sensor. They used 2 different ones but the issue did not resolve. Then they trouble shot the volts etc and finally pulled the pcm out. They claim when they opened the pcm shell it has a burnt odor. I am stopping in tomorrow to speak with them. I can understand a fluke issue but after stranding $1500 on the initial work now I am looking at another $650 or so assuming this fixes my issue. It just seems a little too coincidental with never once in my time owning the car (since 69k miles) did I get a CEL or have any type of electrical issues. The car has been good to me with nothing more than routine maintenance, timing belt, water pump, tires etc. I am wondering if they used the wrong o2 sensor and that fried the pcm but if the CEL came on at first start up post repair I guess the only o2 sensor in the car was the one I replaced 2-3 mo prior. Hard to prove this one.

 

Is this a Honda dealership?

 

No it is an independent shop but I think they called the local Honda dealer to figure out the issue or get advice.