Hey, I have a 99 Volvo V70 T-5 with 130,000 miles. I just replaced the alternator and after starting it up the check engine light came on. I pulled the code and it was P0134, that is the code for the O2 sensor, one of the front ones. Also, lately the car has been having a rough idle (drops about 200-300rpm) intermittently, and there is some white smoke from the dipstick. I am pretty sure the PCV valve is clogged up or the system is shot. I did the whole balloon-on-dipstick test and it didn't start blowing up the balloon (stretch the latex), but did put some smoke into it and made it stand up. The oil is really low (Just under quart low line), I think due to the pcv valve. Could it cause the O2 sensor to not function properly. Let me know what you all think, is it the PCV? Should I just replace the sensor? Thanks

 

Has anyone had a bad PCV system, or clogged valve before? Are there any other symptoms that usually happen with that?

 

Sounds like you need a PCV OH, new O2 sensor (ck this), and an oil change..

And since it's a '99, most likely one of these soon too.

 

thanks, is it possible for something else to cause the engine code though? And if the PCV fixes the rough idle, I think I'll wait on an etm, what would be symptoms of that going bad? probably an rpm problem and surging or something? just curious, why did you type 'PCV OH' what was the OH for?

 

Well I have my new PCV, I was just going to clean the valve, but the hoses look worn. I'll let you know what happens. Still, anybody know of other causes of the o2 sensor code, just so I don't have to buy a new sensor if it's not needed.