P0263: Cylinder 1 Contribution/Balance

What does P0263 mean?

P0263 comes from the cylinder balance control of common-rail diesels: the engine module measures the crankshaft acceleration of each cylinder's power stroke, compares it with the average and gives a deviating cylinder more or less fuel. The code sets when the correction for cylinder 1 reaches its limit and the cylinder still does not keep up – GM at 95 % of a limit of about ±12–17 mm³ for 30 s, Ford above 90 % of the allowed 3.5–15 mg per stroke for 7.5 s; GM needs two trips. The code does not say whether there is too much or too little fuel – the correction value for cylinder 1 shows the direction: strongly negative means a leaking injector, strongly positive a weak injector or low compression. VW and Ram traced some cases to over-sensitive software, so check for updates before replacing injectors.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Rough idle, shaking or knocking
• Loss of power or smoke
• Higher consumption, poor cold start

Common causes

• High Injector of cylinder 1 worn, coked or leaking
• Medium Engine software outdated or diagnosis too sensitive
• Medium Injector correction codes not or wrongly programmed after replacement
• Medium Low compression on cylinder 1 (valve, rings, injector seal)
• Low Crankshaft sensor or tone wheel learning faulty, dual-mass flywheel

Likelihood is a general estimate across vehicles; your make and model may differ.