Ok here is the story. I Have a 1989 240dl sedan. I purchaced the car from my uncle in december 05. Befroe purchaeing it the check engine light kept comming on. my uncle took it to a shop and they told him it was the "brain" ( jettronic computer) he replaced it and that seemd to clear the problem up. He left the orignal computer with the car when I baught it. The alternator went out on the car so I had it replaced and then TA DA check engin light again. I kept smelling gas in the oil so I took it to a Volvo specialist and they said it was one of 2 things the "brain" or o2 snesor. THEY kept telling me they wer 99% sure that it was the "brian" so I had them put the orginal computer back in the car, because I had discoved that the computer in it was from a newer model, and I had a hunch the original was ok. That did not fix the problem so I thought it was headed for the grave yard. I decided to take it to another Volvo speicalist and he told me it was the O2 sensor. He quoted me a price and I said no thanks, buaght an o2 sesor and had my mechanic put it in. TA DA problem fixed. I so the car now has the orignal computer and a new o2 sensor and a new lease on life. How comon is this problem and why would an o2 sensor cause such trouble witht the engine?? thanks
CHRIS