Volvo rookie - 1999 V70XC AWD P0101 P0422 CEL, any tips appreciated!

[jvl]

Hey guys,

Earlier on I created a thread (https://www.matthewsvolvosite.com/forums ... hp?t=77930) when my 1999 V70XC (277K kilometers) started to idle rough and threw the P0101 code. Long story short: replaced the MAF with a used Bosch (identical part number to the one that was installed.) The car now runs fine, the rough idling has completely dissappeared. My problem seemed to be fixed.

However, I have driven 1200 Km with the 'new' MAF sensor, and since I've had the CEL come on twice. The first time it was only one code - P0422. I did some research on this forum and realized I may have not tightened the fuel filler cap correctly. Closed the fuel filler cap correctly, reset the code and have driven for about 700KM when the light came on again today, two codes:

P0101 - Mass or Volume Air Flow Circuit Range/Performance problem
P0422 - Main Catalyst Efficiency Below Threshold (Bank 1)

Today I checked for vacuum leaks by spraying around the engine bay with a can of Starter Fluid. Did not hear the idle change at all. The only thing that might be a symptom is that I'm not sure about the vapour/smoke that comes from the exhaust at a cold start, it's not smoking like crazy but might just be a bit too much. On the other hand, without the CEL I might not even have thought anything of it.

I'm a bit confused since there are no noticeable symptoms (yet ) and I don't know what I can check next to further eliminate potential causes. my next steps will be changing the air filter and possibly installing new o2 sensors. I'm thinking about this because many people seem to have issues with their o2 sensors. Would one or two faulty o2 sensors possibly cause my car to throw P0101 and/or P0422? Or should I look elsewhere?

Any tips or experiences, even brief, are very, very much appreciated.

Thanks!

Joost

[jvl]

Hi all,

Since my last post the girlfriend borrowed my car and.... Check coolant light also lit up. Checked it out, and indeed there was coolant missing. When I bought the car 3000km ago, the coolant level was dead center between MIN and MAX. Topped it up and hope to find out where it's leaking from, i'll keep an eye on all hoses and especially the heater core and expansion tank/filler cap (got a gut feeling that one or both might be bad, since I have no visible leaks under the hood. Did hear a hissing sound though from the expansion tank when I killed the engine, which dissapeared when I tightened the cap).

Any ideas? Could this loss of coolant have anything to do with the car throwing P0101 and/or P0422? Sharing of any experiences with unexplained coolant loss in relation to these codes would be helpful!

Thanks!

Joost