Charge Air Pressure Sensor -G31- Checking

Charge Air Pressure Sensor G31, Checking

NOTE: 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) J220 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.

Procedure







- 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.

If the manufacturers test box is not being used. Perform the following step.
- Remove the Motronic Engine Control Module (ECM) J220.







- Using a multimeter, check the Charge Air Pressure Sensor G31 electrical harness connector terminals to the Motronic Engine Control Module (ECM) J220 electrical harness connector terminals for an open circuit according to wiring diagram.

Charge Air Pressure Sensor Motronic Engine Control Module
G31 electrical harness (ECM) J220 electrical connector
connector terminals test box sockets
1 108
3 98
4 101

Specified value: 1.5 Ohms max.

If the specification was not obtained:
- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).
- If necessary, repair the faulty wiring connection.
- Check the electrical harness connector for damage, corrosion, lose 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) J220.
- 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. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If the DTC memory was erased, generate readiness code.

- End of diagnosis.





With Manufacturer's Scan Tool

Charge Air Pressure Sensor G31, Checking







Special tools, testers and auxiliary items required
- Multimeter VAG1526A or equivalent
- Connector test set VAG1594A
- Adapter VAG1598/31
- Vehicle Diagnostic, Testing and Information System VAS5051 VAS5051 with VAS5051/1
or
- Scan Tool VAG1551 with VAG1551/3A

Requirement
- Vehicle Diagnostic, Testing and Information System VAS5051 or Scan Tool VAG1551 must be connected.

Work sequence

NOTE: The Charge air pressure sensor G31 and its wiring are monitored by the engine control module.

- Read DTC memory of engine control module.

If display shows a DTC relating to Charge air pressure sensor G31 :

Checking power supply







- Disconnect connector - arrow - on charge air pressure sensor.







- Connect multimeter and measure voltage between contacts 1 and 3 of connector.
- Switch on ignition.
- Specification: approx. 5 V

If reading does not match specification:







- Connect test box VAG1598/31 to engine control module wiring harness. Engine control module must also be connected.







- Check for open circuit and short to Ground/positive in following wiring:

Connector contact Test box VAG1598/31 socket
1 108
3 98

- If necessary, eliminate open circuit/short circuit.

If measured value matches specification:

Checking signal wiring
- Connect connector for charge air pressure sensor.
- Connect multimeter and measure voltage at sockets 101 and 108 of test box.
- Start engine and let it idle.
- Specification: approx. 1.90 V
- Increase engine speed by quickly depressing accelerator pedal.
- Specification: 2.00 to 3.00 V

If readings do not match specifications:







- Check for open circuit and short to Ground/positive in following wiring connection:

Connector contact Test box VAG1598/31 socket
4 101

- If necessary, eliminate open circuit/short circuit.

If wiring is OK:
- Replace Charge air pressure sensor G31.