I posted about this before and didn’t get any replies so here goes again with more information. 2003 outback 2.5 about 130,000 miles. CEL on.

code reader says P0030, heated Oxygen sensor, Heater wire circuit, Bank 1 sensor 1.

Turned it off with the reader came back on in about 2 days. Is there a way to check if it is the wiring or actually the sensor that is bad? Another point of confusion is that the part that comes up at Subaru based on my vin is actually an air/fuel sensor not an ox2 sensor. Is that right?

And is the sensor indicated by the code the upstream, or front sensor? And if so how to you get at it? And to you find them easier to get out warm or cold?

I don’t want to spring for a sensor, not cheap, if it is the wiring that is bad.

Thanks for any advice.

http://www.obd-codes.com/p0030

See above link for some general info.

Bank one sensor 1 is the passenger side sensor, BEFORE the catalytic converter .

They can be hard to get out so spray the threads with PB Blaster a few times over a few days before wrenching.

definitely the front sensor. Wouldn't be unusual to be bad at that mileage, but also good to look for other possible causes like wiring.

 

if you replace it, use OEM or Denso part. generics have been reported to not work well.

 

I think there is a way to use an oscilloscope to see if it is swictching correctly.