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) 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. Preliminary Check

Start diagnosis
- Remove the engine cover with air filter.

Test sequence







- Disconnect the Charge Air Pressure Sensor G31 electrical harness connector - 1 -.
- 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) J623.







- 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 an open circuit.

Charge Air Pressure Sensor G31 Motronic Engine Control Module
electrical harness connector (ECM) J623 electrical harness
terminals connector T94 terminals or test box sockets
1 53
3 19
4 38

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, 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.
- Erase the DTC memory. Diagnostic Mode 04 - Erase DTC Memory.
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.

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. Monitors, Trips, Drive Cycles and Readiness Codes

End of diagnosis