Civic4me

Long story short - CEL P0135 never goes away. New OEM O2 upstream sensor (Denso) never fixed the problem. Sensor -heater fuse is good, but P0135 still comes up, it takes about 30 seconds to light up after reset.
Any ideas?
Thank you.

ezone

Have you followed the troubleshooting procedures in the service manual for whatever year car you have?? (05 DX, Canada?)

Does the heater have power?
Does the heater have ground?

What part number sensor did you get?



Did you ever ohm check your original sensor to make sure it was bad before replacing it?
Old sensor heater circuit ohm test is ____?
New sensor heater circuit ohm test is ____?

Civic4me

I did not check manual or power/ground yet, will do. Dont have much time to be honest. The new sensor I bought is the Denso 234-9005.

ezone

Googled diagram looks about like this

Civic4me

Thank you ezone, thats right, I also guessed there should be relay somewhere, and its right there on diagram ) Probably located under glove box, will find it tomorrow )
Thank you.

ezone

Yes behind glove box, there are several relays to choose from.....Check colors of all 4 wires to make sure you have the correct relay

Civic4me

Today I changed all relays behind glove box, same result - no power for O2 sensor heater. I guess ECM is the next step. I can get one for $22. Reprogramming it will cost some money though.
Time for a new car I guess.

​​Sad, because I love my civic.

ezone

A voltmeter (and some thinking) would go a long ways toward actually figuring out what the real problem is.

Civic4me

I already know what's the problem - some fried wires or faulty ECM, in either case it will take too much time to fix.. I might just drive until next emission test comes due, and then I will buy a new car. Will park my civic for later, until kids grow up, then I will be able to spend some time on it.
Thank you.