1999 V70XC...95k miles...I've had code 4801 (catalytic convertor failure) for months...had it in to three different shops - none of them seem convinced the cat is bad. Physical inspection reveals no rattling/etc. Performance and mileage seem fine. Car runs like a dream.

Recently, I've also noticed a pretty substantial oil leak coming out of the (i think) small hole in the oil filler spout. The oil settles in the valve cover, under the plastic cover. I know it is coming out of the hole in the filler spout, because there is oil around the little ledge on the oil filler...which is ABOVE the plastic valve cover.

So, 2 questions. One, my crankcase pressure is obviously too high - something is up with that...any suggestions?

And question 2, could this be the source of my cat code? Could that high pressure somehow be affecting the exhaust system so that my o2 sensors are being tricked into thinking the cat is bad?

I don't want to drop $1k on a cat, only to find out the code remains. I have a hunch the two are related...

Love to hear any comments,

dave

clean the CC vent lines. I don't see a connection between the 2 prob.

I do...more oil vented into the intake (due to high crankcase pressure- clogged pcv system hoses)...burning it with exhaust...messing up the front 02 sensor....CAT cleans it up as much as it can...02 sensor behind the CAT reads even stranger, setting the CAT code and tries to make the fuel/air mixture leaner, which doesn't help. I'd go for a new front 02 sensor if your car is at or above, or even close to 100K miles. Also, I'd get the crankcase vent. hoses cleaned or replaced to lower the pressure in your engine (true cause of your issue)....oil coming up the weep hole is a sure sign this is going on.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.