P0266
Cylinder 2 Contribution/Balance
Fuel injection / cylinder balance
Generic OBD-II
High
What it means
P0266 means the ECM has detected that cylinder 2 isn't contributing its expected share of power compared with the other cylinders. That imbalance usually comes from a weak or leaking fuel injector or from low compression on that cylinder. The engine runs rough and down on power, and a persistent weak cylinder can eventually damage the catalytic converter.
High
Can I keep driving? Driveable but rough — cylinder 2 isn't pulling its weight, so expect a misfire-like miss; extended driving with a weak cylinder can stress the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or noticeable vibration
- Hesitation and reduced power
- Possible increased fuel consumption
Common causes
Most likely first
- Weak, clogged, or leaking cylinder-2 fuel injectorLikely
- Low compression on cylinder 2 (valve, ring, or head-gasket issue)Common
- Injector wiring or connector fault on cylinder 2Common
- Fuel delivery problem (pressure or restriction)Less often
- Faulty ECM (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check cylinder-balance / contribution PIDs to confirm cylinder 2.
- Test the cylinder-2 injector — resistance, and swap or flow-test if possible.
- Run a compression (and leak-down) test on cylinder 2 to rule out a mechanical cause.
- Inspect the injector wiring and connector for damage.
- Replace or clean the injector, or repair the mechanical fault. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0266?+
Only briefly. A weak cylinder runs rough and, if it becomes a full misfire, unburned fuel can overheat the catalytic converter. Get it diagnosed soon.
Can I just clear P0266?+
It returns within a few drive cycles until cylinder 2's injector or compression problem is fixed.
Related codes
Often seen with P0266
Read & clear P0266 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX