Diagnostic Trouble Code (DTC) Information ECM-641F

Condition 

Fig 1: Identifying Camshaft Reset Valve (Continuous Variable Valve Timing (CVVT))

Courtesy of VOLVO CARS OF NORTH AMERICA.

Adaptation of the reset valve (variable valve timing (VVT)) occurs when the engine is running in the event of fuel shut-off (for example, when driving downhill without the throttle closed). In the event of adaptation the engine control module (ECM) checks that the limit positions of the reset valve are reached.

If the reset valve limit positions are not reached during adaptation, the engine control module (ECM) interprets this as a fault and diagnostic trouble code (DTC) ECM-641F is stored.

Substitute Value 

• Shutting off the variable camshaft.

Possible Source 

Faulty signal 

• Loose camshaft position (CMP) sensor
• Incorrect base setting of the timing belt.

Fault symptom[s] 

• Reduction in performance
• The engine misfires
• Uneven idle.