Replaced PCV oil trap and associated hoses. As you can see, it was badly clogged and needed replacement. Cleaned out the ports on the block and put in new unit. Started car, drove for a bit, shut down, restarted and CEL came back, once again with P0079. :twisted: At least it wasn't a wasted repair. ...

So, upon further investigation, I placed a rubber glove over the oil filler opening and it began to inflate, indicating a positive crankcase pressure. Small, barely perceptible puffs of smoke also emitting from dipstick tube when oil dipstick removed and oil filler cap in place. All very strong indi...

Same thing here. Replaced the solenoid and gasket and still getting the error code.

I realize this is 2+ years on, but how did you resolve the issue?

My 2005 XC 90 threw a P0027 (exhause valve solenoid) error code, immediately after changing the oil. I assumed the exhaust solenoid became clogged, and so replaced the solenoid with a brand new part and gasket and now the P0027 error has been replaced with P0079 (exhaust circuit low) error code. I c...