P1303 Diagnostic Trouble Code (8 interpretations)

The control module registered the fault condition described as "Heated Catalyst Internal Control Module Checksum/ROM Error". This is the manufacturer-specific definition used by BMW.

The control module registered the fault condition described as "EGR Calibration Fault". This is the manufacturer-specific definition used by Ford.

The control module detected crankshaft speed fluctuations consistent with combustion misfire (Cylinder Number 3 Random). This is the manufacturer-specific definition used by Honda.

The control module detected that the TDC signal stayed above the expected range. This is the manufacturer-specific definition used by Hyundai.

The control module detected crankshaft speed fluctuations consistent with combustion misfire (Cylinder 3). This is the manufacturer-specific definition used by Land Rover.

The control module detected a fault associated with the Misfiring Cylinder 3 circuit or function; the stored code identifies the affected component rather than a single failure mode. This is the manufacturer-specific definition used by MINI.

The control module detected a fault associated with the Misfiring Cylinder 3 circuit or function; the stored code identifies the affected component rather than a single failure mode. This is the manufacturer-specific definition used by Mitsubishi.

The stored code identifies a fault of the Knock detector fault. Documented for the Bosch MED 17.4.x engine ECU (EP6 THP family) on Peugeot applications; the same PSA control units are also fitted to Citroën models. PSA documentation does not characterise the failure mode further.