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Check engine light flashing: Codes, Causes & Fixes

A flashing check engine light almost always means an active, severe misfire. Unburned fuel then reaches the catalytic converter, where it can overheat and damage it within a short distance. Ease off the throttle, avoid hard acceleration, towing and highway speeds, and get the car checked as soon as possible; if the engine shakes badly or you smell burning, stop and arrange a tow.

22Codes
3.2Average severity
14%High or critical
9%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 P0301 Powertrain Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector… Moderate

All codes (22)

All Severity 3+ Severity 4+
P0201 Powertrain The ECU sees an open or faulty electrical circuit to injector 1, so cylinder 1 is probably… Moderate P0202 Powertrain Injector 2's circuit is open or out of range; on an inline-four it's a middle cylinder under… Moderate P0203 Powertrain The ECU sees no normal electrical response from injector 3: its coil, its wiring or its driver… Moderate P0204 Powertrain The circuit to injector 4 is open or out of range; on most transverse engines that's… Moderate P0205 Powertrain The ECU sees a broken or faulty electrical circuit to the cylinder 5 injector, so that cylinder… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0301 Powertrain Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector… Moderate 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 P0305 Powertrain Cylinder 5 is misfiring. First job: work out which bank it sits on, because that decides what… Moderate P0306 Powertrain Cylinder 6 is misfiring. On an inline-six it's the hot rear cylinder; on GM and Hemi V8s it can… Moderate P0307 Powertrain Cylinder 7 is misfiring. On GM and Hemi V8s it's a cylinder-deactivation cylinder, so check… Moderate P0308 Powertrain Cylinder 8 is misfiring. It's a rear V8 cylinder against the firewall, so its plug is often… Moderate P0354 Powertrain Coil D, normally the one on cylinder 4, failed its circuit check. It often shows up right after… Moderate P0356 Powertrain The coil F circuit for cylinder 6 failed its check. On inline sixes it's the coil… Moderate P0358 Powertrain Coil H, for cylinder 8, has an electrical fault. On nearly every V8 it's the hardest coil… Moderate P1320 Nissan · Powertrain The Nissan ECM isn't seeing the ignition primary signal it expects while the engine cranks… Moderate 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 P1399 Honda · Powertrain An older Honda's PCM counted misfires that jump between cylinders instead of staying in one. Moderate P3400 Powertrain Cylinder shut-off on bank 1 (AFM, DFM, MDS or VCM) isn't doing what the engine computer… Moderate

Symptoms

Check engine light on 558Loss of power 214Rough idle 184Limp mode 165Poor fuel economy 146Engine stalling 133Car won't start 123Harsh or slipping shifts 80ABS / traction light on 65Fuel smell 34