Symptoms
- Light blinks or flashes rather than staying solid
- Engine may feel rough, jerky, or lose power
- Possible smell of unburned fuel or light popping sounds from exhaust
Likely causes
- CommonEngine misfire from a bad spark plug or coilUnburned fuel dumps raw fuel into the hot catalytic converter.
- CommonFailing ignition coilCoils wear out individually and often trigger a specific cylinder misfire code.
- PossibleFuel injector problemA stuck or clogged injector disrupts combustion in one cylinder.
- PossibleLow fuel or bad fuel qualityWater or contaminated fuel can cause temporary misfires.
- Less commonVacuum or head gasket issueMore serious and usually comes with other symptoms like white smoke.
What to do
- Ease off the accelerator and avoid hard acceleration or towing while the light flashes.
- Find a safe place to pull over if the engine feels rough or is losing power.
- Avoid continuing to drive far; a flashing light means active damage risk to the catalytic converter.
- Get the vehicle to a mechanic or have it towed if it's running very poorly.
- Have the code read to identify which cylinder or system is misfiring.
- Ask the shop to inspect spark plugs, coils, and injectors for that cylinder.
- Replace the failed part(s) as recommended rather than just clearing the code.
- Avoid resetting the light yourself if you plan to have it diagnosed, since codes give the mechanic a head start.
When to call a pro
Have a mechanic diagnose it the same day; don't keep driving normally with a flashing light.
Safety
Use caution
A flashing check engine light means stop hard acceleration and towing; driving far can destroy the catalytic converter, which is expensive to replace.