P0266 Cylinder 2 Contribution/Balance Fault

P0266 indicates a cylinder 2 contribution or balance fault. Cylinder 2 is contributing less or differently than expected.

Code details

Generic OBD-II · P0

System: Injector
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace injector 2 from a contribution code alone; verify mechanical and fuel delivery causes first.

Symptoms of P0266

Check-engine light, often with a misfire feel from one cylinder.
Rough idle, hesitation, or a slight loss of power.
Higher fuel use, or in some cases a fuel smell.

Common causes of P0266

A stuck, leaking, clogged, or electrically failed injector.
Injector wiring, connector, or driver-circuit faults.
Low fuel pressure or contamination affecting injector behaviour.

Useful checks before replacing parts

Compare cylinder 2 contribution, misfire counters, injector balance, compression, fuel pressure, and ignition or glow data if equipped.
Inspect injector flow, injector command, wiring, compression, intake leaks, exhaust leaks, and fuel contamination.
Check whether the imbalance occurs at idle, under load, cold, hot, or with companion injector circuit or misfire codes.

Related OBD-II codes

These nearby injector entries can help compare wording and pin down the fault area.