Charge Air Pressure Sensor, Checking

Special Tools And Workshop Equipment 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 

Start Diagnosis 

-- Remove the engine cover. Refer to the appropriate Service Information.

Test Sequence 

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

-- Start the engine.

-- 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 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-. Refer to the appropriate Service Information.

-- 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 terminals for an open circuit according to wiring diagram.

Charge Air Pressure Sensor -G31- electrical harness connector terminals	Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminals or test box sockets
1	13
2	Empty cavity
3	27
4	39

Specified value: 1.5 Ω 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 if the voltage supply was OK: 

-- Replace the Charge Air Pressure Sensor -G31- Refer to the appropriate Service Information.

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 the appropriate Service Information.

-- Install the engine cover. Refer to the appropriate Service Information.

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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .