P0266 - Cylinder 2 Contribution/Balance Fault
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
The Engine Control Unit (ECU/PCM) monitors each cylinder's individual contribution to the engine's total torque by measuring variations in crankshaft rotational speed during the power stroke. If the ECU detects that the acceleration of the crankshaft is significantly lower for cylinder 2 compared to the other cylinders, P0266 is set. This indicates incomplete combustion or mechanical inefficiency in that specific cylinder. The system uses high-resolution signals from the Crankshaft Position (CKP) sensor to calculate acceleration for every 180-720 degrees of rotation.
Possible Causes
Faulty or clogged fuel injector for cylinder 2
Damaged or worn wiring harness to the injector (high resistance or intermittent contact)
Mechanical engine issue in cylinder 2 (low compression, worn valves, or piston rings)
Faulty Crankshaft Position (CKP) sensor or damaged tone ring
Internal ECU software error or driver circuit failure
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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