What is P0056 and P0154
 

I have a 1999 S80 T6. It gives me P0056 and P0154. I did a search on this forum, but didn't find any of them.

Any idea what is the problem. Thanks.

Vic

P0056 is rear 02 sensor bank 2 (drivers side) heating circuit faulty.
P0154 Is front 02 sensor bank 2 no activity.

Most likely you need both new sensors.

Tech, thenk you for your prompt reply.

Just curious, if an O2 sensor is remove dfrom the car, how can we test it - to see if it is still working or not.

You would have to read real time data with it in the car through a scanner.
You could not test it out of the car.

You can get O2 sensors really cheap at amazon right now. I just bought an front one for around 80 and it works well. It retails for like 350 or so. Maybe you can get it for around 200 but not 80. FYI.