Hey everyone,

Just wanted to get some expert opinions on my options to spend as little $$$ as possible on my trusty ****ebox

Just failed the CA smog check & here are the fault codes from the test.

P0135 Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Heater Circuit Malfunction

P0420 Catalyst System Efficiency Below Threshold

P1456

This has been a problem before the last check 2 year ago but then it passed. In the past the CEL would come on & go off on it's own but for the last year has been on full time. MPG is around 30 even though I wring it's neck everyday.

I have the test results with a lot of data I can post if needed.

TIA
Steve

 

Sounds like a new oxygen sensor is in your future. That'll probably clear up the first two codes.

 

Unplug the primary O2 sensor (closest to the engine) and measure the resistance between the two wires on it that are the same color, which is the heater circuit. I think 10 to 40 ohms is the spec for good. Finding an open circuit, sensor is definitely bad.

 

Thanks...I will try that.

 

That was it. Open circuit on old sensor & with new sensor no CEL & seems to run a bit better.