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Hi group - I could use a point in the right direction in isolating check engine light and trouble codes. I have zero history on the car but here's the situation. Engine was not idling well and it was running a little sluggish. I replaced plugs and wires (AC Delco) and put in a new battery. Started the car and no check engine light but after letting it come to temp, check engine came on. I took it for a drive and at first it was a little sluggish but once I drove it on the interstate it began running much better and idled fine. I'm thinking the initial sluggishness may have been due to it not being driven in 4 months and moisture i fuel line. Anyway, took it to Autozone to pull codes which showed P0603, P0141 and P0300.

Before I pull the coil packs to do the ohm testing and before I look at O2 sensor, I thought I'd see what you guys think. All input and help is much appreciated!

Thanks, cal

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Yes, your heater on an o2 sensor is bad, but unfortunately i don't think it explains a misfire when the engine gets warm. There are no codes what explain your misfire. Being you replaced plugs, and wires, i suspect it can be a bad / faulty under load coil. Unfortunately, your codes are not equipped to tell you which coil pack is bad. After you run thru a fresh tankful of gas without resolution, you might have to start testing and swapping the coils.

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Change the o2 sensor asap. I recommend denso, no bosch.

Drive it like you stole it and if it still seems to run sluggish check the coils,

Welcome To Caddyinfo you have come to the right place


Nice, clean, luxury= fine automobile

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