P02B4 - Cylinder 6 Injector Data Compensation Error at Maximum Limit
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P02B4 is stored when the Engine Control Unit (ECU) reaches its maximum adaptive fuel trim limit for cylinder 6. The ECU is attempting to compensate for a lean condition by increasing the injector pulse width (Duty Cycle) but has hit the calibrated threshold without achieving the stoichiometric target. This indicates that cylinder 6 is experiencing an under-fueling condition or unmetered air ingress. The ECU monitors individual cylinder power balance via crankshaft speed fluctuations and O2 sensor feedback.
Possible Causes
Clogged or partially restricted fuel injector (Cylinder 6)
Intake manifold vacuum leak or gasket failure specific to cylinder 6
High electrical resistance in the injector wiring or connector
Mechanical engine fault (e.g., leaking valve or low compression on cylinder 6)
Faulty ECU injector driver circuit
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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