What it means
The ECU compares each cylinder's contribution to crankshaft speed (rough run analysis) and determined cylinder 2 contributes less or more than the average. This points to a mechanical or fuel delivery problem rather than a pure ignition fault.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module estimates how much each cylinder contributes by measuring small changes in crankshaft speed. This code means cylinder 2 is contributing differently from the others, which can happen when its injector is restricted or worn, or when cylinder 2 has low compression.
Common causes
Most likely first.
- Injector clogged or worn
- Low compression on cylinder
Symptoms
- Check-engine light
- Rough idle or engine vibration
- Reduced power
- Engine misfire
How to diagnose it
- Review freeze-frame data, cylinder 2 misfire counts, and any available injector balance or rough-running data to see when its contribution falls behind.
- Inspect cylinder 2's injector connector and wiring, and check for intake or exhaust leaks near that cylinder that could affect its contribution.
- Compare cylinder 2 injector operation or balance with the other cylinders using a scan tool and the vehicle's specified test method.
- If injector operation is suspect, check cylinder 2 fuel delivery and injector condition against the manufacturer's specification.
- If fuel delivery is satisfactory, perform a compression test on cylinder 2 and compare the result with the other cylinders and the manufacturer's specification.
Common fixes
- Repair a loose or damaged cylinder 2 injector connection or wiring found during inspection.
- Clean or replace a restricted or worn cylinder 2 injector if testing confirms poor delivery.
- Repair a leak affecting cylinder 2 if inspection identifies one.
- Repair the mechanical cause if cylinder 2 compression is below specification.
Can I keep driving?
A brief, gentle drive may be possible if the engine is stable, but avoid heavy loads and prolonged driving while cylinder 2 is misfiring. Stop if vibration becomes severe or power drops sharply; continued misfire can damage the catalytic converter.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.