Diagnostic trouble code (DTC) information ECM-640A

Condition

Fig 1: Identifying Camshaft Position Control

Courtesy of VOLVO CARS OF NORTH AMERICA.

The engine control module (ECM) checks that control of the intake camshaft is rapid enough by measuring the time taken to deploy the camshaft to the requested angle.

The diagnostic trouble code (DTC) is stored if the engine control module (ECM) detects that deployment of the camshaft is too slow (signal too high) or to slow when the camshaft returns (signal too low).

The diagnostic trouble code (DTC) can be diagnosed by the engine control module (ECM) when the engine coolant temperature (ECT) is above a certain value, the engine is running at least at idle speed and when camshaft control is active.

Substitute Value

None.

Possible Source

Signal too high

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

Fault symptom[s]

Malfunction indicator lamp (MIL) lit
High emissions
The engine cuts out when driving.