Can anyone tell me the symptoms I will get if I have a bad O2 sensor?...
I can drive for about 15 minutes.....my cel lite comes on...and its as if I ran out of gas. If I let it sit for an hour....its ok again...for another 15 minutes.
I check the codes with my ignition and gety a 12..then 21..then 55.
I presume that is a bad O2 sensor.
Can this be my cel problem?. I have a 95 neon 2.0 liter

 

21 is an O2 sensor code, but there are 2 O2 sensors, and each has 4 or 5 different things that could be throwing the code. If you are anywhere near an Autozone, they'll pull the 4-digit codes for free and that will narrow things down a lot... Since your car is a '95, they'll tell you you don't have OBD-2. You do. So you can either tell them it's a '96, or pop the hood and show them the emissions information sticker that says "OBD-2", then kindly direct them to the OBD-2 port down under the light switch. I usually go for the 2nd option, AFTER betting the poor sap a soda...

Best of luck!

 

thank you.....but what are the symptoms of a bad O2 sensor??

 

oh...I forgot to mention...I am in Canada......not that that matters...but up here...Canadian Tire wants $85 to throw there tester on my car. Im trying to avoid that if I can...

 

For $85, you can buy your own... I'd be calling around ot different shops and parts stores, I know there's a better price.

Since there are a number of things that can cause a "bad" sensor, there's not an easy list of symptoms. It could make the car run too rich, or too lean, flip flop back and forth between the two, or just act up occasionally. Generally it's just poor running, maybe the occasional backfire, sputtering on acceleration, poor idle, and the list goes on.

Find the O2 sensor that is between the head and the cat. Follow the wiring back a ways. I'm wondering if your wires aren't rubbing up against the intake manifold or the axle (very common) and shorting out. I've had the same problem recently, just took a few tie wraps and some electrical tape to fix. Worth looking at anyways, and a heck of a lot cheaper than a new sensor.

 

I'd say the most common and noticeable for me is the drop is mpg with a bunk O2.