| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuits are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. Variable Valve Timing (VVT) sensor may also be referred to as camshaft position sensor.
Circuit Description
The Variable Valve Timing (VVT) system controls intake valve timing in response to driving conditions. Engine Control Module (ECM) controls Oil Control Valve (OCV) to ensure correct valve timing. A OCV is located in cylinder head at timing belt side of engine. Oil pressure controlled by the OCV is supplied to the VVT controller. VVT controller then changes relative position between camshaft and crankshaft. VVT controller is located on the front of intake camshaft. DTC P1656 is set if ECM detects an open or short in OCV circuit. Possible causes are
- OCV circuit is open or shorted.
- Defective OCV.
- Defective ECM.
Diagnostic Aids
Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.