Fuel Pressure Sensor, Checking

Special Tools And Workshop Equipment Required 

• Multimeter.
• Wiring diagram.

Test Requirements 

• The Fuel Pump (FP) Control Module -J538- OK.
• The Motronic Engine Control Module (ECM) - J623- fuses OK.
• The fuel filter OK.
• The Battery voltage at least 12.5 V.
• All electrical consumers switched off (radiator fan must NOT run during test).
• A/C switched off.
• The fuel tank at least ¹ /₄ filled.
• The ignition switched off.

Test Procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis

-- Remove the engine cover with air filter. Refer to the appropriate Service Information.

Checking voltage

-- Disconnect the Fuel Pressure Sensor -G247- electrical harness connector.

-- Switch the ignition ON.

-- Using a multimeter, check the Fuel Pressure Sensor -G247- electrical harness connector -1- terminals for voltage.

Fuel Pressure Sensor -G247- electrical harness connector terminals	Specified value
1 to Battery positive (+)	Battery voltage
2 to Ground	Near 0 volts
3 to Ground	5 V

-- Switch the ignition OFF.

If the specified value was obtained:

-- Replace the Fuel Pressure Sensor -G247- : Refer to the appropriate Service Information.

If the specified value was Not obtained:

Checking wiring connections

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 Fuel Pressure Sensor -G247- harness connector terminals to the Motronic Engine Control Module (ECM) -J623- harness connector for an open circuit according to the chart below.

Fuel Pressure Sensor -G247- electrical harness connector terminals	Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminals or test box socket
1	13
2	40
3	29

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.

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

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the appropriate Service Information.

-- Install the engine cover with air filter. 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 .