My 1999 Saturn SL2 recently showed the “Service Engine Soon” light. Since the local Firestone charged $100 just for diagnostic, I brought it to Autozone for a code scan. They told me it is P0133, and could be due to a bad oxygen sensor.
I tried calling a couple mechanics for quote.
Most quoted a diagnostic cost around $100 and won’t give further estimate. One local store quoted me $240+tax for replacing O2 sensor. Firestone gave me the estimate $300-600 for O2 sensor replacement. I am puzzled by this as both RepairPal and WebMD report a price much lower than this.
I am a student and don’t have any experience with car problem diagnostic, hence I don’t have any information on vacuum leak / wiring… The only two pieces of info I have is that:
a) my car recently passed emission test mandated by my county, and thankfully the Service Engine Soon light comes on about a week AFTER the check
b) my car usually runs fine with no problem, only that my wife notes that it starts to “shake” when I drives over 65MPH or turns on cruise control. I have noticed a slight drop in fuel economy - from 22.5-24.5MPG to around 21MPG
I don’t make much at all and $300-600 seems like a pretty big dent in my budget. And I am going to graduate in around one year. Not sure if it is worth the money for the repair. Do you have any suggestion for me? If it were indeed the O2 sensor problem, what might happen if I don’t replace it? Thank you!