Hi. I'd welcome some advice for my 2001 H6 Outback. Not long after I bought it I noticed an intermittent problem with the Check engine light coming on (at same time as VDC Off light being illuminated). A quick check with Torque confirmed the error code as P0031 Bank 1 Sensor 1 which i took to be the offside front Sensor (UK). Deleting the code made it go away for a couple of weeks but on hot starting occasionally back it came. So I replaced the sensor last week and cleared the codes. Everything went well for a couple of days.

 

Today the error code came back. Same error code but the description was slightly different  "HO2S Heater Control circuit low (Bank 1 Sensor 1)"

 

Is this likely on a brand new sensor or could it point to a duff connector or something else duff with wiring between the sensor and the ECU?If the latter how would I go about checking.; Any advice gratefully recd.

 

O2 front sensor #1 could be failing the air/fuel ratio. If its done a lot of miles, this is a possibility.

Cheers. The car has done 167k miles. Any idea of a poss solution. I don't really want to shell out on a 2nd new sensor unless it's necessary. Love the car and want it to run as it should.

Can you swap the front and rear over ? If it shifts the code to the one that you know is good then may not be the sensor it's self

That sounds like a plan. I had not thought them interchangeable but I suppose I could swap left and right front to get the same effect. Tks for the tip. will try this tomorrow and see what happens.

They may not be interchangeabl, not sen the new age ones but I thought it may be worth a mention to try before splashing more cash

Will try to swap left to right front then and see what happens.

This afternoon I changed back to the previous sensor, ensuring that the connection was extra secure and so far so good.

Success was short lived. The old sensor started playing up but a) not as much as the new sensor and B) only on hot start-ups i.e when the engine was thoroughly up to temperature. I have checked the connector and it looks sound but wonder if there is a further connection upstream between the existing connector and the ECU?