I recently change my O2 sensor on my 2000 chevy silverado. after replacing bank 1 and 2, I reset the it with the code reader. The check engine light went out but came back on again. Any idea?


Asked by Feb 20, 2014 at 09:09 PM about the 2000 Chevrolet Silverado 1500 Ext Cab Short Bed 4WD

Question type: Maintenance & Repair

My truck wont pass smog.The original code was PO300. It was random misfire, I was
told. I ask my buddy who is a mechanic in Arizona he advise me to change O2 sensor in
stream bank 1 & 2. And to reset it using the code reader. after changing both sensor and
resetting it. The light went out but eventually came back on again. but now the code is
PO 134 and 154. Ideas? Thanks.

13 Answers


Those codes state the the sensors you just put in show no activity, so either there is a wiring problem with the O2 sensor circuits or the sensors you bought are bad. Random misfire can be caused by partial plugged injectors, bad fuel, low fuel pressure, worn spark plugs, high resistance in the ignition system, low coil output. ust a few things to check. HTH

3 out of 3 people think this is helpful.

I'd put the old O2 back in and then go from there.

1 out of 1 people think this is helpful.

Yes, code P0300 is random/multi-cylinder misfire. For the P0300 code I'd do a tune up first. Especially if you've got over 100,000 miles on your Silverado. I'd try and return those oxygen sensors, you probably didn't need them. Put the old oxygen sensors back in, tune it up, clear the computer, drive it, and let us know. HTH. -Jim

1 out of 1 people think this is helpful.

p0300 has nothing to do with o2 sensors

2 out of 2 people think this is helpful.

I put back the old O2 sensor and did a tune up. Reset the computer and drove it around, the check engine came back on and so did the PO300 code.

1 out of 1 people think this is helpful.

p0300 engine misfire. On the 4.3 vortec you need to test fuel pressure leakdown to make sure the fuel pressure regulator isn't leaking causing the misfire. What items include your tune-up?

5 out of 5 people think this is helpful.

Check for good strong spark and injector spray at all the cylinders. A bottle of fuel injector cleaner wouldn't hurt as well. HTH -Jim

2 out of 2 people think this is helpful.

oh, this is probably a 4.8 or 5.3. for some random reason i thought it was a v6... on those a p0300 is pretty hard to find with no other codes. Usually a bad coil or injector gives a local misfire (ex: p0301). Its gotta be something central like MAF, fuel pump, vacuum leaks, coil, cam sensors. things like that.

1 out of 1 people think this is helpful.

Can't return o2 sensor cause its electronic I don't think. What is bank 1 & 2?


Bank 1 is the side of the engine that the #1 cylinder is on. Bank 2 is the side of the engine that the #2 cylinder is on. With an inline engine everything will be bank 1. HTH. -Jim

A o2 sensor can throw a code of p0300. I just had a o2 s3nsor go bad it was throwing code p0155, p0059 and p0050 and p0300. Changed the o2 sensor drove it all day never had a code at all. The 02 sensor regulates many things. And it can cause a misfire.

What I can suggest when you get random misfire Po 300 my experience usually it's the catalytic converter.failing I would start with plugs wires coils and Oxygen sensors. My truck has 330, OOOO miles on it. As it has aged the engine has not used oil but. The mileage and wear internallly in the engine tend to contamination the spark plugs quicker. THE Catalytic converter last approx 100,OOO before I start getting the misfire codes. MagnaFlow seems to make the best aftermarket catalytic

check you distributor and see if the gear has thinned just fixed a tuck the other day that had the same issue and the disturber gear was bad.

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