Charge Air Pressure Sensor, Checking

Diagnostic Procedures

Charge Air Pressure Sensor, Checking

Observe all safety precautions: --> [ Safety Precautions ]

View clean working conditions: --> [ Clean Working Conditions ]

Prior to repair work, perform a preliminary check to verify the condition. Refer to --> [ Preliminary Check ] Preliminary Check.

• The Charge Air Pressure Sensor and IAT Sensor are combined and must be replaced as a unit.

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of the IAT sensor (G42).

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 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.

Test sequence

- Disconnect the Charge Air Pressure Sensor/IAT sensor (G31/G42) electrical harness connector.

- Turn ON the ignition switch.

- Using a multimeter, check the Charge Air Pressure Sensor/IAT sensor (G31/G42) electrical harness connector terminals 1 to 3 for voltage.

Specified value: Near 5 V

- Using a multimeter, check the Charge Air Pressure Sensor/IAT sensor (G31/G42) electrical harness connector terminals 1 to 4 for voltage.

Specified value: Min. 4.40 V

- Switch the ignition off.

If either specified value 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/IAT sensor (G31/G42) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623)electrical harness connector T60 terminals for an open circuit according to wiring diagram.





Specified value: 1.5 ohms max.

If the specified value was Not obtained:

- Check the wiring for an open, high resistance or short to ground.

- 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 the voltage supply was OK:

- Replace the Charge Air Pressure Sensor/IAT sensor (G31/G42).

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

- Replace the Motronic Engine Control Module (ECM) (J623).

- Install the engine cover.

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 Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to --> [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to --> [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.