2000 Volvo V70 XC--Check Engine Light!

[Ozark Lee]

Expanding on what 850tech said. My one and only cat failure was comprehensive, if you crawled under the car and smacked it (the catalytic converter) all you got was a sound like it was full of gravel. While I don't think it was converting anymore and the noise it made gave it up sooner than the CEL.

...Lee

[adk793]

Yeah, makes sense. Here is the thing, the CEL turned itself off yesterday, which is not a bad thing. But now when i plug in my OBDII scanner, im not getting a response from any of the emission systems. Like ussualy, i plug it in, and i have a bunch of little icons symbolizing the different systems, and if all are working, they glow up, or if not, they blink meaning something is wrong or pending. What could this mean

[850tech]

Disconnecting the batt for 5 mins might help the no communication problem, also if the Batt falls bellow 11v the system may not communicate as well. Though to say really.

As far as the light comming back and going out, it really sounds like the rear O2s going south, if it were the cat the light would come back after 2 decent 20 min+ drive cycles and NOT go away.

[Retired MVS Contributor]

On my 2001 XC70 the vacuum routing diagram is on the rear of the hood on the driver's side...It is the same diagram another member posted here for you...It is a good bet that yours is in the same place...

[v70xclace]

I realize this post is a little dated but, maybe my experience can help someone else... My 99 v70 xc 's engine light came on the other day. Exactly like the original poster above, it went on right after a hard acceleration into Turbo (and shortly after a second tank of regular unleaded got pretty low) I went straight to AutoZone to have the code read and they said either the front o2 sensor or the catalitic converter. I read on here that someone fixed theirs by creating a lean mix by removing a vaccuum hose for a few minutes. The lean mix burned hot and burned off the buildup on the o2; engine light went off. Rather then messing with hoses I decided I'd try running some high octane fuel. I filled my tank with premium feul and added an octain booster/cleaner. 40 miles later the engine light went off and no problems since. That $10 bottle of octane booster saved me (potentially) hundreds of dollars!