Replaced both o2 sensors but still check engine light
 

Initially I had codes P0154, and P0157 which indicate Bank 2 sensor 1, and sensor 2 are both suspect. I changed both sensors with Bosch replacements (not generic, but original volvo replacement numbers).

Now the car runs great, but I can't get rid of a P0156 code. The code relates to O2 sensor circuit malfunction on Bank 2 sensor 2. That's the sensor I just replaced!

I've tried the battery disconnect trick, the holding the battery cables together for an hour once the battery had been disconnected, and clearing the codes only to have the check engine light reappear.

Any ideas what I should try next?

Thanks

Whoops. That would be a 1999 S80 T6 I'm talking about. 125,000 miles.

i had this issue twice, the first time it went away for about a year, the second well i still have it now

my MPG and performance is great so im not gona bother, but there is a problem somewhere. its pretty stupid, never had that on any other car

Could it be that your connection isn't tight enough?

Thanks! The connection had come loose on the O2 sensor. All is fantastic now.....