About 3 years ago I installed my 3" turbo back and just chopped out and then re-soldered on my rear 02 sensor and of course it threw the CEL but I didn't care as I knew it was just for emissions.

But now I've decided to part with my DSM and need that stupid CEL to go off so I can sell it. I went out and bought a brand new Bosch 02 sensor and installed it. CEL goes off for about 20 miles (one trip) and then it comes back on.

I get out the old OBD2 reader and pull the code: p135, a rear heater circuit malfunction (same code BEFORE I replaced the sensor). I did some research and found that maybe the first mistake I made was going Bosch instead of OEM as that can cause problems as the application claimed by the manufacturer isn't always the correct one.

Searching here I found mention that the code p135 could be the front O2 sensor (which after 85k miles I don’t think has ever been replaced). Could this be the case? As my research has pointed me towards the conclusion that the rear sensor would be the cause for this code, any clarification would be appreciated.

So now I’m debating what I should do; replace the front 02 sensor, re-replace the rear 02 with an OEM sensor or wander down to radio shack and buy the materials needed to bypass the rear O2 sensor.

Naturally I don’t want to waste money on replacing crap anymore than I have to so constructive input would be greatly appreciated on the subject.

I know the problem isn’t a failed/clogged cat because it has less than 5k miles on it and it’s high flow 3” just like the exhaust.

Don't rig something up to make the CEL go away so you can sell the car. That can get you in trouble years down the road should someone discover it (since it's emissions related). There's different codes for front and rear O2 sensor malfunctions. I don't have them handy, but the code does tell you exactly which one needs replaced. Personally, I'd junk that Bosch either way and put an OEM on...

Once you correct the CLE, just make sure you sell the car "AS IS" and make sure the new owner is aware of the modificaitons so he/she cant come back at you later down the road. Just make sure the words "AS IS" are clearly stated in some kind of sales agreement.

Yeah that's for the advice on selling the car guys but that isn't really what I asked about

The whole "don't mess with the emissions" is a moot point since this car hasn't been "street legal" in years nor will it be when I sell it "as is" for "off road use".

P135, is or is not the back sensor? Since I have read documentation that says it is the rear sensor but posts on this site have suggested that it could be the front as well this is my biggest concern.

So far that’s 1 for “lose the Bosch” which I’ll likely have to do.

Anyone else?

I believe it is the forward sensor. I looked up the code and it said sensor one and from my experience, the forward sensor (closest to engine) is sensor one. I did a quick look and this is what I got on the code. I apologize that I don't have a better answer, my guide is at home.

http://72.14.203.104/search?q=cache...mitsu/+p0135+eclipse&hl=en&gl=us&ct=clnk&cd=6

Excellent! Thank you for that information. I guess it’s time for me to do the old “swap parts” until it goes away.