Rep Power: 0

Hi all,

I wonder if anyone has seen a sensor fault like this before? I've looked around and can't seem to find anything specific to my circumstances.

I bought a 2001 Civic Se Auto a few months back as an emergency car and it turned out to be pretty reliable so I've kept it for now.

The only issue I have is an odd P0135 error code (Bank 1 Sensor 1 O2 heater) .

I can see from the service history the previous owner had reported an intermittent issue and a garage had changed the sensor.

I've checked the heater contacts and it shows 10 Ohms which is probably expected but the harness side shows 0 Volts with key turned to 2/engine off. I do read 12V between hot and the Neg battery terminal though.

Do I assume correct that this is likely now an ECU issue as I've read somewhere that the ECU switches the ground and not +12V?


The circumstances it illuminates are the oddest part..

If the light is off (no code) fuel consumption seems quite high.

When light is on fuel consumption is usually OK ~400miles off 50L

Driving normally will eventually turn light off but code will remain present. Performance is usually OK (it's never going to break records though being what it is)

And the strange bit... If I've cleared the code, the only way I've been able to get the light to come on in the first place is to floor the accelerator and get up to max speed or close to it and hold that speed for a while, and only on easing off the accelerator does the light illuminate. The car will already be warm at this point and I'd think there'd be no need for the heater in the first place.

 
Rep Power: 134

P0135 is a malfunction in the Primary O2 Sensor 1 Heater Circuit Malfunction either from a poor connection, loose terminals, faulty primary O2 sensor, a short or open in the wires in the circuit or a faulty PCM.

Chances are good that you just need a new Primary O2 Sensor - use only an OEM Denso sensor - no BOSCH or similar.