Camshaft Position Sensor: Testing and Inspection

Camshaft Position (CMP) Sensors, Checking

Special tools, testers and auxiliary items required
- Multimeter V.A.G 1526 or equivalent.
- Test Box 105 Pin VAG1598/42.
- Adapter Lead Vag1598/39 VAG1598/39.
- Adapter cable V.A.G 1598/39-1.

NOTE: Use only gold-plated terminals when servicing terminals in harness connector of Camshaft Position (CMP) Sensor G40.

Test requirements
- Fuses for Engine Control Module (ECM) J623 OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N" .
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.

Checking activation







- Remove engine cover - arrows -.
- Disconnect the electrical harness connector - 1 - at Camshaft Position (CMP) Sensor G40.
- Using the Voltage Tester VAG1527B or equivalent, check for voltage between terminal 1 and terminal 2 with the electrical harness connector connected to Camshaft Position (CMP) Sensor G40.
- Operate the starter briefly.

The 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.

- Switch ignition off.

If the LED does not blink:

Checking voltage supply







- Using the Multimeter V.A.G 1526 A or equivalent, check the following wiring connection for voltage.

Harness connector Terminal Measure to
1 Engine Ground (GND)

- Switch the ignition on.
Specified value: about 5 V.
- Switch the ignition off.

Checking signal wire







- Using the Multimeter V.A.G 1526 A or equivalent, check the following wiring connection for voltage.

Harness connector Terminal Measure to
2 Engine Ground (GND)

- Switch the ignition on.
Specified value: approx. battery voltage.
- Switch the ignition off.

Checking Ground (GND)







- Using the Multimeter V.A.G 1526 A or equivalent, check the following wiring connection for voltage.

Harness connector Terminal Measure to
3 Battery positive (+)

Specified value: about 10 V.

If the specified values are obtained:
- Replace Camshaft Position (CMP) Sensor G40.

If the specified values are not obtained:

Checking resistance

- Connect the test box 1598/42 to the wiring harness of the Engine Control Module (ECM) J623.







- Using the Test Box 105 Pin VAG1598/42 and Multimeter V.A.G 1526 A or equivalent, check the following wiring connections for an open circuit.
- Camshaft Position (CMP) Sensor G40 (bank 1).

Harness connector Terminal Test box Socket
1 Battery positive (+) 26
2 (signal) 44
3 Ground (GND) 14

Specified resistance 1.5 Ohms max.

- Check the wiring for a short circuit to Battery positive (+) or an open circuit.
- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:
- Replace the Engine Control Module (ECM) J623.

Assembly is performed in the reverse order of removal, note the following:

Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

- End diagnosis and switch the ignition off.