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Check engine light on--P codes coming up

I had the sparks and wires replaced in my 2003 Mini Cooper when the service engine light came on (66k miles). After several startups, the light went out, as it should’ve. Then my son filled the car with regular gas (it requires 91 octane min.)and the light came back on. Autozone checked the codes: P0304 (cylinder misfire) and P0313 (low fuel). I’m hoping that a fuel additive and a full tank of premium will clear this up, but, if it doesn’t, it’s back to the mechanic. What do you car mavens think?

I’m hoping that a fuel additive and a full tank of premium will clear this up,

Would be nice it that one ever really worked.

How old are the plugs and plug wires? How many miles does it have and when was the last fuel filter change? Were you allowing the fuel to go close to empty in the tank?

The P0313, “misfire with low fuel”, could be from low fuel pressure. The troubleshooting charts would help, but, in their absence, I’d change the fuel filter, and check the fuel pressure and the fuel pressure regulator.

Forget the additive, it won’t do anything. When the regular gas is completely gone the light may go off on its own. I’d keep filling it with premium and be patient.

I’d also give the kid a dope slap.

plugs and wires are new (forgot to add that). when they were replaced, one of the parks was definitely bad. after replacement, the light went out (after several startups).

what i also forgot to add is that, besides the low octane gas, i think the cold weather has something to do with this. yesterday, with temps in the 40s, the light went out. when the temps fell, the light came back on.

re the additive: so this stuff doesn’t work? why?

thanks!

whats a DOPE SLAP? anywhere near the mud flap.