P0266: Cylinder-two contribution is judged against available fuel correction

P0266 is cylinder two’s contribution/balance code. In Ford’s documented 6.7L cold-start strategy, the controller flags correction greater than 90% of the allowed fuel-balancing correction for the current operating conditions. The number describes how close control effort has moved to its limit; it is not a measurement that cylinder two produces only 10% power.

The permitted correction changes with operation

The source ties the allowance to operating conditions, so one fixed correction value cannot be substituted for the percentage test everywhere. The cold check operates between 500 and 3,000 rpm with injection quantity of 3.5–90 mg/stroke. Typical detection duration is 7.5 seconds.

Completed wheel learning and valid crankshaft diagnostics are required. These prerequisites distinguish a meaningful balance result from an observation made with an uncertain rotational reference.

Interpret the recorded mode

Ford also lists a general fuel-balancing check with its own conditions, including no regeneration. A cold-start P0266 should be evaluated in its actual mode; a smooth warm idle does not directly reproduce the cold opportunity.

The code identifies cylinder two within a shared monitor family. It does not state that a particular injector, compression fault, or wiring problem is the cause. Preserve related circuit and crankshaft faults, confirm cylinder numbering for the engine, and use the applicable diagnostic procedure to separate causes. The manufacturer’s summary describes the correction boundary, not a cylinder-two parts-replacement recipe.

Source and applicability

This explanation follows Ford’s 2023–2024 diesel OBD summary. Match the vehicle’s engine and calibration before applying these monitor values; a generic code alone does not establish fitment. Ford PDF, page 19 · Ford PDF, page 59.