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Ignition & Misfire Trouble Codes: List & Fixes

P03xx codes cover misfires and the sensors the engine needs to time ignition. P0300 means random or multiple misfires; P0301 to P0312 name the cylinder that is misfiring; crankshaft and camshaft position sensor codes also sit in this range. On coil-on-plug engines, swapping the coil from the misfiring cylinder with a neighboring one and seeing whether the misfire follows is a quick, cheap first test. If the check engine light is flashing, reduce load and get the car checked promptly to protect the catalytic converter.

66Codes
3.0Average severity
15%High or critical
12%DIY-friendly
Severity distributionSeverity distribution

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P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate P0303 Powertrain Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame… Moderate P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate P0325 Powertrain The computer isn't getting a usable signal from knock sensor 1, so it pulls timing to protect… Low P0335 Powertrain The engine computer lost the crankshaft position signal. Expect stalling or a crank-no-start. High

All codes (10)

All Severity 3+ Severity 4+
P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0320 Powertrain The computer lost the engine speed (rpm) signal. The engine can stall suddenly or refuse… High P0335 Powertrain The engine computer lost the crankshaft position signal. Expect stalling or a crank-no-start. High P0337 Powertrain The crank sensor signal line is stuck near 0 volts, usually a wire shorted to ground. Often… High P0338 Powertrain The crank signal line sits at 5 or 12 volts and stops switching: open ground, open wire… High P0339 Powertrain The crank signal drops out for moments at a time. Classic sign: stalls when hot, restarts once… High P1326 Hyundai · Powertrain Hyundai's KSDS software heard vibration typical of worn rod bearings and put the engine in limp… Critical P1326 Kia · Powertrain Kia's engine computer detected early rod-bearing wear through the knock sensor and capped… Critical P1340 Volkswagen · Powertrain The cam signal no longer lines up with the crank signal – often a jumped belt or stretched… High P1362 Honda · Powertrain The PCM gets no signal at all from the top dead center (TDC) sensor; stalling or a no-start… High

Subsystems

Fuel & Air Metering 193Emission Controls 97Speed & Idle Control 57Transmission 57ECU & Outputs 54Module Communication 43Brakes, ABS & Chassis 36Body Systems 31Hybrid / EV 14