~ Dazed and Confused ~

I have a '96 Grand AM 2.4L and have a check engine light on for over a year. Every time I go for an oil change, a mechanic diagnoses it for free (hoping I will get it fixed), and they all tell me different problems:

Firestone diagnoses - Both O2 sensors and catalytic converter have gone bad
Repair estimate: $800

Meineke Car Care - One of the O2 sensors bad (don't know which one), catalytic converter low.
Repair estimate: $500

Gary's Garage - Catalytic converter is fine (after mechanic tested it by putting some computer next to the tail pipe), O2 sensor might be bad, or just some wire under the car is pulled off.
Repair estimate - Anywhere from $100 - $400

Monroe Muffler and Brake - Mass airflow sensor bad, giving reading of 4.0 (not sure what that means)
Repair estimate - not provided as they don't repair this.

Recently my alternator went bad too, I wonder if that check engine light had to do anything with it.

Also my car shakes real bad at 50+ speeds and while braking (or when car slows automatically while going uphill).

WHAT SHOULD I GET REPAIRED? O2 SENSOR or MAFS? HELP!!

i would get the o2 sensors repaired and see if the light goes out. I would buy them and put them in myself would really save you lots of money they are not that hard to put in pretty easy. Good luck FrankC

Know of any guides that I can use to do that? Because ones I buy that part and couldnt put them on would really fuck me over.

As EZFrank said the best place to start is with the O2 sensors. You can purchase a Haynes manual for your car at an Autozone or buy either a Chiltons or Haynes from Amazon.com. The O2 sensors are located on the exhaust pipes after the gasses exit the engine. There should be one in front of and one behind the Cat. To remove them simply rent or buy an O2 sensor socket or if they aren't too tight you can use channel locks or a regular wrench. The other thing to remember is to put antiseize on the threads. You may need to take it back to a garage to turn the CEL light off by clearing the codes.

As for the shake above 50 mph, you need to have the brakes looked at sounds like warped rotors, you can replace these yourself if you have some simple hand tools, the repair manual will tell you how to do it. Finally, you may also want to get your axle shafts checked. When they start to go bad they will vibrate usually at speeds above 50 mph and once the reach a speed above that will smooth out and the vibration will go away. You may want to leave this repair to a mechanic. Good Luck!!!

As for the shake above 50 mph, you need to have the brakes looked at sounds like warped rotors

Thanks for your reply. But doesn't sound to me like brakes have anything to do with this. The car jerks going uphill OR while braking. Basically when anything slows it down and the car is at 50-60 mph it jerks.

But I well get the sensors fixed. I probably will take it to a shop for that, cuz (a) i dont have the time to do this myself (b) if I didnt do it right, it would cost me hell lot more.

As EZFrank said the best place to start is with the O2 sensors. You can purchase a Haynes manual for your car at an Autozone or buy either a Chiltons or Haynes from Amazon.com. The O2 sensors are located on the exhaust pipes after the gasses exit the engine. There should be one in front of and one behind the Cat. To remove them simply rent or buy an O2 sensor socket or if they aren't too tight you can use channel locks or a regular wrench. The other thing to remember is to put antiseize on the threads. You may need to take it back to a garage to turn the CEL light off by clearing the codes.

As for the shake above 50 mph, you need to have the brakes looked at sounds like warped rotors, you can replace these yourself if you have some simple hand tools, the repair manual will tell you how to do it. Finally, you may also want to get your axle shafts checked. When they start to go bad they will vibrate usually at speeds above 50 mph and once the reach a speed above that will smooth out and the vibration will go away. You may want to leave this repair to a mechanic. Good Luck!!!


As far as the shaking is concerned your control arms could be going. I have a 97 and both of my lower control arms have had to be replaced at one time or another and yes when the first one started getting worn out the car shook a little. Mechanic said the are around the bushings was worn out.