Bought a 2001 beautiful V40 from a used car dealer two weeks ago. During the emission test (in Virginia, that happens after the purchase instead of before the sale) the check engine light came on, P0133, O2 sensor. Dealer offered to replace it so I can pass emission. After replacement, the light never went away after multiple reset, and did not pass the re-test. Dealer again replaced the 4-day old O2 sensors (Bosch), thinking maybe it was defective. Again, check engine light did not go away, and OBD II scanner still says O2 sensor. We are out of ideas, and no mechanic (tried three shops) can figure out WHY it keeps giving a P0133 code after replacing the O2 sensor. Unfortunately, this little light would not let me pass emission, so the dealer is offering a FULL REFUND. He will probably just auction this beautiful car (one owner, california) off due to this STUPID GOD DAMN light.

Should I just take the money and walk, giving up on this car?

 

On S40 I notice after replacement of O2 sensor u need to reset the adaptation on the engine control module. (DEALER SPECIFIC TO RESET ADAPTATION) Also there is a pig tail harness that is needed to install between the O2 sensor harness and the harness from vehicle... I never have a come back after that...