1996 honda accord, I get check engine light and code for the oxygen sensor immediately after starting the engine. I used to get this code 3 years ago that came on after like 60 miles of driving and cycling the speed due to a bad cat but bypassed that by "moving" the oxygen sensor outside the exhaust stream and hadn't had an issue since. But now it comes on immediately when starting the car. This makes me think it is not functioning at all or the heating element is dead if it doesn't even let the sensor do it's thing to test exhaust gases at temp. I think there is only a single o2 sensor even though autozone has part numbers for pre and post cat so I am hoping someone knows the correct number.

Does anyone have any thoughts on getting this code immediately when starting up or think the sensor must be totally at fault, or know what fuse to check possibly?

Trying to pass inspection in a few weeks and ironic that it happens now.

Thank you

 

obviously the oxygen sensor heating element is bad like you say....when you take your test and fail you will need to replace the cat and the upstream oxygen sensor with a Denso oxygen sensor and you should put it back the way it was....the oxygen sensor actually has a purpose and putting it outside of a "sealed" exhaust system defeats that purpose.

 

should be code p0135. Could be the heating element or wiring harness itself? I'm just asking b/c if i just go under and replace the sensor itself without rewiring back to the engine, i might find it still in check. Where do i find the fuse or connection where it runs back under the hood?

 

So is it 0135 or 0145?

Also is this a 4 or 6 cyl?

 

Yeah, P0135. 4cyl. Why do they list pre and post cat part numbers for 02 sensor when there is only one on this model and year?

 

Because there are two

 

Yes you are absolutely correct. Thought I was told only one but my memory sucks. I see them both now so looking back, I threw a p140 and fixed that by messing with one on the cat. So p0135 code for sensor 1 should refer to the one on the manifold yes?

Also why when the one on the cat went, it took some driving to get it to throw a code after resetting but now after resetting p0135, it fails and throws check engine light at startup. Sound logical?