P0031 H02S BANK 1 SEN 1
Heater Circuit Low

I am getting these two error codes. I'm assuming the first one is the 02 sensor but does anyone know which one? I read somewhere that there is one before and after the cat. Also, any ideas on the "heater circuit low"? Thanks in advance!

Edwin

 

I believe the first code is for the pre-cat O2 sensor, as I know that after-cat code is different (P0036 or something like that). No idea about the heater circuit. Maybe someone else can chime in on that one.

 

I only see one code, P0031. I believe O2 sensor is heated, maybe that's the circuit that's reading low.

 

Update: I replaced the o2 sensor and reset the error with a diagnostic tool... and the light came back on with the same error message. Any ideas?! I'm assuming there's only one o2 sensor right?

Edwin

 

There are two o2 sensors - one before and one after the cat.

 

Hopefully you replaced the b4 cat o2 sensor. That's the fault you got stored. second, you need to reset the adaptation values for the heating circuit. Without reseting the values, the car still see a bad heating circuit even though the sensor was replaced. Or drive the car around for about a week and then clear the fault, this gives the car long enough to reset adaptations on its own. Hope this helps.