I have a 99 s70, the check engine light came on, had it scanned and came up with code po135 o2 sensor bank 1 sensor 1. i replaced the part and the light is still on. i cleared all codes and the light comes right back on with the same code.
i called the dealership and he said something about needing a software update if you do anything with the electric system. never heard of that before.
any help would be greatly appreciated

 

Did you use a Bosch sensor?

 

no, it was a denso 234-9020

 

Is the car turbo or Non?

 

non turbo

 

OK then the denso sensor is correct. How fast does it come back?
Maybe try to disconnect the battery for like 10 minutes to reset the ECU and see if the code stays away.
You will need to make sure you have the radio code before disconnecting the battery though.

Sometimes it takes the ECU a while to see the new part is in there.

 

it comes back on the second time i start the car. ill try disconnecting it again see what happens.

i disconnected it again for over 10 minutes and it came right back on.

 

have you driven the car for at least 10 minutes? when i replaced my coolant sensor it took ten minutes for it to "recognize" it and turn the cooling fan off....

 

yes, i have driven the car almost 1000 miles since changing it.

 

I had the same problem with the CEL. A mechanic friend told me to disconnect the negative battery terminal and then turn the headlight switch to on -- leave for 10 minutes and it worked.... maybe I was lucky.....

 

yea tried that too, it wasn't the issue here but got it off by disconnecting it and recounting the o2 sensor. im a chevy guy theis volvo stuff is throwing me off.