P0263 — Cylinder 1 Contribution/Balance Fault
The ECU compares each cylinder's contribution to crankshaft speed (rough run analysis) and determined cylinder 1 contributes less or more than the average. This points to a mechanical or fuel delivery problem rather than a pure ignition fault.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Fuel injector
- Cylinder compression
- Intake valve
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Injector clogged or worn
- Low compression on cylinder
- Localized intake leak
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.