Diagnostic Trouble Code (DTC) Information ECM-640A

Condition

Fig 1: Identifying Variable Valve Timing (VVT) Unit

Courtesy of VOLVO CARS OF NORTH AMERICA.

The engine control module (ECM) checks that the actual camshaft angle position (actual value for the camshaft shift angle) corresponds to the requested angle position (target value for the camshaft shift angle). The diagnostic trouble code (DTC) is stored if the value for the actual camshaft angle position is higher (signal too high) or lower (signal too low) than the control module target value for the camshaft angle position.

The diagnostic is active when the engine is running, engine at operating temperature.

Substitute Value

None.

Possible Source

Signal too high

Poor engine oil quality
Damaged camshaft reset valve
Mechanical fault in the continuous variable valve timing (CVVT) unit.

Signal too low

Short-circuit to supply voltage in the signal cable
Poor engine oil quality
Damaged camshaft reset valve
Mechanical fault in the continuous variable valve timing (CVVT) unit.

Fault symptom[s]

Malfunction indicator light (MIL), on
Uneven idle
High emissions
The engine cuts out when driving.