P0263 Cylinder 1 Contribution/Balance Fault

P0263 points to a cylinder 1 contribution or balance fault. Cylinder 1 is not contributing power as expected compared with the other cylinders.

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 1 from a balance code alone; verify fuel, compression, and control data.

Symptoms of P0263

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 P0263

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 1 contribution, misfire counters, injector balance, compression, fuel pressure, and ignition or glow data where applicable.
Inspect injector flow, injector command, wiring, compression, air leaks near the cylinder, and fuel quality or contamination.
Check whether the imbalance is idle-only, load-dependent, temperature-related, or paired with injector circuit or misfire codes.

Related OBD-II codes

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