Charge Air Pressure Sensor, Checking

Charge Air Pressure Sensor, Checking

• Use only gold-plated terminals when servicing terminals in harness connector of Charge Air Pressure Sensor (G31).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Motronic Engine Control Module (ECM) ( J623 ) fuses OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• On vehicles with automatic transmission, selector lever in position " P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Remove the engine cover with air filter.

Test sequence

- Disconnect the Charge Air Pressure Sensor (G31 ) electrical harness connector - arrow -.





- Start engine and let it run at idle.

- Using a multimeter, check the Charge Air Pressure Sensor (G31) electrical harness connector terminals 1 to 3 for voltage.





Specified value: min. 4.5 V

- Switch the ignition off.

If the specification was not obtained:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

- Install the Test Box 105 Pin (VAG1598/42).

If the manufacturers test box is not being used. Perform the following step.

- Remove the Motronic Engine Control Module (ECM) ( J623). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

- Using a multimeter, check the Charge Air Pressure Sensor (G31) electrical harness connector terminals to the Motronic Engine Control Module (ECM) ( J623) electrical harness connector T94 terminals for resistance.









Specified value: 1.5 ohms max.

If the specification was not obtained:

- Check the wiring for an open circuit, short circuit to each other, Battery (+), and Ground (GND).

- If necessary, repair the faulty wiring connection.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace the Charge Air Pressure Sensor (G31)

If no malfunction is detected in the wiring and if the voltage supply was not OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

- Install the engine cover with air filter.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.