Questions and Answers

Buick Century DTC P0301
Q. Dear Sir: I own a 1999 Buick Century, 3.3 liter V-6. The "Service Engine Soon" light came on a while back and I haven't had much luck getting it to go off. I brought the car to Auto Zone for a free "Error Code Scan" and it showed "error code" P0301 which indicates a misfire in cylinder #1. They recommended changing the spark plugs.

I brought the car to a mechanic and he changed the plugs and also said the ignition coil for that cylinder needed to be changed also. When I got the car back the light was out and I thought the problem was solved.

By the time I got home to my garage, a few blocks from the shop), the light came back on. And it's been on ever since.

The car never felt like it was misfiring or running badly, although I think my gas mileage has gone down considerably. I don't want to bring it back to this mechanic because I'm afraid he will change more parts and not solve the problem.

I'm up for and State Inspection soon and would like to resolve this problem. Any help you can provide for this problem will be greatly appreciated.

Thank you very much.
Very truly yours,
Robert

A. If the code is still P0301...this means the PCM is seeing a misfire on #1 cylinder. Chances are good that you have a clogged injector for that cylinder.

You may try cleaning them with the GM approved method or just replace it. Cleaning may fix it though. It should have a fuel injector balance test to determine if the injectors are dirty. Try a dealer for this one.