P1638 Diagnostic Trouble Code (8 interpretations)

The control module detected improper operation of the Alternator ‘F’ terminal circuit. This is the manufacturer-specific definition used by Chevrolet.

The control module detected improper operation of the Motor control module (MCM) - internal circuit. This is the manufacturer-specific definition used by Honda.

The control module detected improper operation of the ECM (Microcontroller). This is the manufacturer-specific definition used by Hyundai.

The control module detected a fault associated with the CAN Link ECM INSTM Circuit Network circuit or function; the stored code identifies the affected component rather than a single failure mode. This is the manufacturer-specific definition used by Jaguar.

The control module detected the fault condition "ECU internal fault" for the Engine ECU. Documented for the Bosch EDC16C34 injection ECU (DV6TED4 1.6 HDi) on Peugeot applications; the same PSA control units are also fitted to Citroën models.

The control module detected a fault associated with the Immobilizer information mismatched circuit or function; the stored code identifies the affected component rather than a single failure mode. This is the manufacturer-specific definition used by Suzuki.

The control module did not receive the expected Data Bus Powertrain signal. This is the manufacturer-specific definition used by Volkswagen.

The control module detected a fault associated with the Engine control module (ECM), internal temperature high - stage 2 circuit or function; the stored code identifies the affected component rather than a single failure mode. This is the manufacturer-specific definition used by Volvo.