Low Fuel Pressure Sensor, Checking

Diagnostic Procedures

Low Fuel Pressure Sensor, Checking

The following procedure requires a test drive. Observe all safety precautions. Refer to => [ Safety Precautions ] Safety Precautions.

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuel Pump (FP) Control Module (J538) OK; check.

• The fuel filter OK.

• The fuses for the engine electronics OK.

• The parking brake engaged.

• The battery voltage at least 12.5 V.

• The selector lever of automatic transmission in position "P" or " N".

• 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

- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions

- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Checking voltage

- Disconnect the electrical harness connector from the Low Fuel Pressure Sensor (G410).

- Switch the ignition on.

- Using a multimeter, check the electrical harness connector for voltage.









- Switch the ignition off.

If specified value is obtained:

- Replace the Low Fuel Pressure Sensor (G410)

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 Repair Information.









Specified resistance 1.5 ohms max.

If the specification is not obtained:

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

- If necessary, repair the wiring connection.

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

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

- Assembly is performed in the reverse of the removal.

Final procedures

After repair work, the following work steps must be performed in the mentioned 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.