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Misfiring 00 impala

I have a 2000 Chevy Impala LS the other night on my way home from work I noticed the check engine light flashing when I accelerate I was losing power on the accelerate and when I got home I open the hood and let it run and my engine was running really rough and had a like a shake to it and noisier than normal you could feel the vibration in the car like the rattle so I had the codes read and I’ll include pictures of what it said anybody have any ideas I mean it says I have a bad EGR valve but could that cause the symptoms? I can tell the rattle is from the misses.

Showing p0300 random misfire detected
P0141 o2 heater circuit bank 1 sensor 2

The code P0141 indicates that the O2 sensor after the catalytic converter has a problem with its heater circuit. It usually means the heater in the O2 sensor has failed.

The P0300 code is indicating that there’s a major misfire occurring because the Check Engine light is flashing.

The vehicle shouldn’t be driven while the Check Engine light is flashing as this can cause damage to the engine/catalytic converter.

This means it has to be determined what’s causing the misfire before driving the vehicle again.


Without doing in depth diagnosis, a good place to start is changing spark plugs. The most common cause for missfires are bad plugss. If it’s not plugs, you didn’t lose anything, cause it’s probably due any ways. Seeing that it is a random missfires, it is more likely to be one of your coil packs. I believe that there will be two plugs on each coil pack. One way to find which coil pack it is, is to pull a plug wire from a plug while it is running. If it doesn’t change the engines behavior you fond which cylinder is misfiring. Then reconnect plug and then pull the wire from the plug from the corresponding coil. If that didn’t change the engines performance, you found the bad coil. But beware, this is not a recommended way to do it, as disconnecting plug wires can damage coils. I’ve done it many times without incident, but at my own risk. If you want to do it right, you should get a spark tester and check for spark that way. After you get the misfire taken care of, then you can address the OWNER sensor. That sensor does not affect engine performance. Once you get the misfire fixed, clear the codes, and see if the code comes back, then it would be the time to change sensor or check circuit.

Why did you call the oxygen sensor an “owner” sensor and in all caps?

Goofy auto correct. O2 sensor. Wow it worked that time.

Autozone said that second code was an egr valave??? So its an o2 sensor?

Tester supplied the correct code definitions.

Your original post

There’s a 15 amp fuse for the O2 sensor heaters, so check that. Junction block A, underhood. the heater coil in the sensor itself should measure 5-6 ohms, another thing to check.

If you actually do have a faulty EGR valve that’s allowing too much exhaust into the intake manifold, that indeed could cause severe misfires and pop a p0300 code. the two p-codes you posted however are not for the egr. A typical EGR p-code is p0401.

Never trust what the guy at Autozone tells you the codes mean. Get the actual codes and look them up yourself using any internet search engine. The guys at Autozone are parts jockey’s for a reason, they are NOT mechanics!

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