Codes P0301 and P0455

LREAZIN1

MEMBER
2004 CHEVROLET IMPALA
3.4L
V6
2WD
AUTOMATIC
150,000 MILES

Car gives codes P0301. I have replaced plugs, wires, coils, AIC valve, cleaned, MAF sensor, throttle body. Still have same problems rough idle stalling at low rpm misfire occasional code p0455. Live data says heated catalytic converter is registered but not complete. Also catalytic converter isn't registered or complete and it always needs coolant but no sign of leaks.

1 Reply

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

The two Direct Trouble Codes[DTC][s] are probably going to be linked together. DTC P0301 is a DTC for a misfire in cylinder 1 and DTC P0455 is a DTC for a large EVAP leak. The only thing that I would recommend checking that you didn't already do for DTC P0301 would be to swap fuel injectors between cylinders 1 and 2 and see if the DTC follows the fuel injector to cylinder 2. If it does then you know that it is a bad fuel injector. Also you might want to do a compression test to rule out that as a cause for the misfire. Here is a link to a guide explaining how to do a compression test below:

https://www.2carpros.com/articles/how-to-test-engine-compression

In the diagrams down below I have included the diagnostic troubleshooting guide for DTC P0455 from the vehicle manufacturer for this vehicle. Please go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

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