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 distribution

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P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate P0301 Powertrain Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector… Moderate P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0307 Powertrain Cylinder 7 is misfiring. On GM and Hemi V8s it's a cylinder-deactivation cylinder, so check… Moderate P0305 Powertrain Cylinder 5 is misfiring. First job: work out which bank it sits on, because that decides what… Moderate

All codes (3)

All Severity 3+ Severity 4+

P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at 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

Symptoms

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