The 600 was for a tune up as they couldn't exactly diagnose the problem, this also included a new factory O2 sensor as the code reader was telling them it needed to be replaced. They didn't even mention the possibility of the EGR valve. That would have probably been another 2 or 3 hundred. After...
I just want to say that you people ROCK!!!!
A few months ago I brought my '01 Protege in to get checked out as it was idling rough and the check engine light came on. They gave me an estimate of over 600 bucks because they said the code is showing a bad o2 sensor. Well, I've been putting it off...