Camshaft Position Sensor: Testing and Inspection

Camshaft Position (CMP) Sensor 2 -G40-, Checking

Special Tools and Equipment







- VAG1526A
- VAG1527B
- VAG1594A
- VAG1598/31

The Camshaft Position (CMP) sensor provides the ignition position for cylinder 1.

For failure, knock control is switched off and the ignition angle is retarded slightly since a cylinder allocation is no longer possible. In addition, the boost pressure of the turbocharger is decreased.

Engine will continue to run without Camshaft Position (CMP) sensor signal and can also be restarted:
- When a malfunction is recognized, the Engine Control Module (ECM) initiates one ignition spark per cylinder for each crankshaft rotation.
- The offset of one engine rotation will have no noticeable effect on the injection. Instead of occurring with intake valves open, injection will be "pre-loaded" (in front of closed intake valve). This has only a minor effect on the quality of the mixture preparation.

Checking activation
- If installed, slide back the rubber grommet on the connector for the Camshaft Position (CMP) sensor, but leave the connector connected.







- Connect VAG1527B voltage tester between sockets 2 (CMP sensor signal) and 1 (B+).


NOTE: Connector socket numbers are shown on the rear side of the connector.


- Operate starter for a few seconds.
- LED must blink.


NOTE: Voltage testers do not go out completely during low current pick-up between activations by the ECM, but rather continue to glow a little and then get significantly brighter during activation.


If LED does not blink:

Checking voltage supply
- Disconnect connector at Camshaft Position (CMP) sensor.







- Connect multimeter for voltage measurement as follows:







- Switch ignition on.
- Specification: about 5 V

Checking signal wire
- Connect multimeter for voltage measurement as follows:







- Switch ignition on.
- Specification: approx. battery voltage

Checking Ground (GND) wire







- Check the following wire connection for open circuit and short circuit to B+:







- Repair open circuit or short circuit if necessary.

If all specified values are being reached and the LED does not blink (measured between terminal 1 and 2 with starter and connector connected):
- Replace Camshaft Position (CMP) sensor.

If specified values are not obtained:

Checking wire connections between Camshaft Position (CMP) sensor and Engine Control Module (ECM)

- Connect VAG1598/31 test box at wiring harness to Engine Control Module (ECM), do not connect ECM. Refer to "Scan Tool Testing/Wire and Component Testing Using VAG1598/31 Test Box" Testing and Inspection








- Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:







- Repair open circuit or short circuit if necessary.
- If, after erasing DTC memory for the sake of the test, a DTC relating to the Camshaft Position (CMP) sensor (hall sensor) is indicated again, even though all previous tests were OK, the following malfunction is possible:
- Shutter wheel for Camshaft Position (CMP) sensor is not aligned properly.
- Unscrew Camshaft Position (CMP) sensor and check whether shutter wheel is mounted properly at camshaft (if mounted improperly, locking lug will get squished when mounting bolt is tightened).
- If position of shutter wheel is OK, check allocation of crankshaft/camshaft.