[laserx]

A month ago I got CE light on, had it checked and it came up knock sensor and 02 sensor 3 I believe (it's the 02 senor on the exhaust pipe after the engine), both were replaced at the Subaru Dealer. Anyway, after a week CE came back on, I took it back and he cleared the CE a week later it came back. I then left my car with them as I went on a holiday for two weeks with instruction to fix everything they could find wrong. Over $2000.00 later I picked up my car all was perfect...for 9 days and once again CE light same 02 senor. I'm thinking I have a defective 02 sensor, the mechanic now says it must be the MAF causing the 02 senor fault to show up and they want over $500.00 for the part. I still think they should try another 02 sensor before I shell out $500.00 for the MAF. My question, is the mechanic right and should I just go for the new MAF or should I insist on trying a new 02 sensor first. (anyone got a used MAF for sale?)

Oh ya to add to this, my transmission has now gone insane, works perfect sometimes and sometimes will not shift up into 4th gear, just rev's like crazy, it's going into the transmission shop on Friday.