● Stop driving
Driving on can cause serious damage or leave the car stranded.
Driving on can cause serious damage or leave the car stranded.
The engine computer sees misfires on cylinder 1. The driver usually notices rough idle, shaking and weak power, and the engine light may flash.
Guided check
- Is the engine light flashing?If yes: Stop driving and reduce load. A flashing light means unburnt fuel can damage the catalytic converter. Find the misfire before any road test.
- Does the misfire move when you swap the coil to another cylinder?If yes: The coil is the likely cause. Replace it and clear the code, then road test.
- Are the spark plugs worn, oily or wet?If yes: Replace the plugs. If they are oily or fuel wet, also find out why before finishing the job.
- Is the compression low on the misfiring cylinder?If yes: This is a mechanical problem such as valves, rings or head gasket. Do a leak-down test before ordering parts.
These checks are general and are still being reviewed by working mechanics.
Causes vary by car. Test before you order a part.
Likely causes, most common first
- Worn spark plug
- Faulty ignition coil
- Clogged or faulty fuel injector
- Low compression on cylinder 1
Parts usually involved
- Spark plug Find at suppliers
- Ignition coil Find at suppliers
- Fuel injector Find at suppliers
Test before you replace
Swap the coil and plug with another cylinder to see if the misfire follows, then test the injector and compression on cylinder 1.
General guidance for generic OBD2 codes. Always follow the maker's procedure for the car in front of you.