Hi - first post here, so please feel free to re-direct me to the correct forum if necessary. I have a 2003 WRX wagon, with a TurboXS and some other mild exhaust manifold mod. I bought it new, and it has been trouble-free for 50K+ miles. A while ago the CEL came on. I bought a cheap OBD code reader, and got the following codes:

P0031 (H02S) Bank 1 Sensor 1 Heater Circuit Low
P0546 Exhaust Gas Temp. Sensor Circuit High (Bank 1 Sensor 1)
P0134 O2 Sensor CKT No Activity (Bank1 Sensor 1)
...plus a P0031 code pending

Clearing the codes extinguishes the CEL for about 10 seconds, and then another P0031 code appears.

So I Google'd/Bing'd the topic and get lists of codes & the text above, and other abstruse threads of people with situations different from mine. My question is - anyone know exactly what this means, and how I might fix it (myself maybe?) My first guess is that an O2 sensor has gone bad.

Any comments very much appreciated....Chris

 

Sounds like the O2 has gone bad. I would replace that first.