Diagnostic trouble code (DTC) information

Condition

Fig 1: Identifying Camshaft Position Angle

Courtesy of VOLVO CARS OF NORTH AMERICA.

The control module checks that the camshaft is in the correct position in relation to the position of the crankshaft. If the position of the camshaft is incorrect, the control module will adjust the adaptation for the camshaft. Diagnostic trouble code (DTC) ECM-643A or ECM-644A is stored if the adaptation becomes too great.

Substitute Value

None.

Possible Source

Signal too high

Poor oil quality
Incorrectly adjusted camshafts
The timing gear belt has jumped off the cogs
Defective reset valve
Mechanical fault in the variable valve timing (VVT) unit.

Signal too low

Poor oil quality
Incorrectly adjusted camshafts
The timing gear belt has jumped off the cogs.

Fault symptom[s]

Malfunction indicator lamp (MIL) lit.