99 Saturn SL2 P0133 -- limited budget, what to do?

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 :slight_smile:
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!

The code indicates the O2 sensor has stopped cross-counting. Or stopped switching voltage.

You can get an O2 sensor from Rockauto.com for about $25.00. http://www.rockauto.com/catalog/moreinfo.php?pk=3426774&cc=1357264

Then ask around if anyone knows someone who wrenches on cars. Since this is the bank 1, sensor 1 O2 sensor, it should be easy to change out on your engine.


If it just passed smog, your catalytic converter is still good. If you don’t change the sensor, the converter could go bad if the sensor is really off. The price of that is anywhere from $500 to $2,000. Yours is probably on the cheaper side of that.

If the catalytic converter goes completely out, your hydrocarbon emissions could go to 400 PPM instead of 80 PPM. It could be worse than that but you personally won’t be trashing the environment. I would say to have the sensor changed.

A relative may be willing to give you some money. If you can’t call a friendative, you can call around to service stations to get the lowest price for the job. As always, good luck with the search. If you are living in one of those cities with a professional sports team, you may not find prices lower than the $300.

Thank you both for your response! Thankfully a friend who knows a little about auto repair can help me take a look. I will forward your advice! Thanks again!