I replaced the front 02 sensor on my wifes 2000 V70 and then was able to clear error code P0135, started the car up and drove it for a while.I figuredIhadfixed the problem. Then my wife drove the car later that day and the same code came up. I can still clear the code and drive the car, but whenever I shut it down and turn it back on the code reappears.Any ideas what I did wrong or what the problem maybe?

 

OEM (Bosch)sensor?
If not that may be the problem.

 

Is P0135 low flow on sensor 1 or something like that??I had to do two things replace the sensors with OEM and the cat sensor was bad (wires were falling out of the sensor). The cat sensor can say trip low flow on sensor 1 when the cat sensor is the really the ONE that is bad. If you use the universal bosch sensor I say good luck ,it's a total nightmare!!!! O$$$E$$$M$$ only