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DTC codes / U03xx · Software and configuration mismatches / U0309

U0309Software Incompatibility with Alternative Fuel Control Module

U0309 is a network communication code indicating that the alternative fuel control module (AFCM) reports a software version or calibration that is incompatible with what the powertrain control module (PCM) expects. The PCM has detected a mismatch in software identification or configuration data over the controller area network (CAN) bus, so it cannot trust or coordinate with the alternative fuel system.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaSoftware and configuration mismatches

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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