Fuel Metering Valve, Checking

The following procedure is used to diagnose the Fuel Metering Valve -N290- which is controlled byEngine Control Module -J623-.

Special tools and workshop equipment required 

• multimeter.
• Wiring diagram.

Test requirements 

• The Engine Component Power Supply Relay -J757- OK.
• The Fuse -SB5- OK.
• The fuel filter 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.
• 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 three screws -arrows- and the engine lifting eye to gain access to the electrical harness connector.

-- Disconnect the Fuel Metering Valve -N290- electrical harness connector -2-.

Checking internal resistance

-- Using a multimeter, check the Fuel Metering Valve -N290- terminals 1 to 2 for resistance

Specified value: 450 to 1000 Ω.

If the specified value was not obtained:

-- Replace the Fuel Metering Valve -N290-. Refer to the appropriate service information

If the specified value was obtained:

Checking voltage 

Crank the engine.

-- Using a multimeter, check the Fuel Metering Valve -N290- electrical harness connector terminal 1 to Ground (GND) for voltage.

Specified value: battery voltage.

-- Switch the ignition off.

If the specified value was not obtained:

-- Check the wiring from the Fuel Metering Valve -N290- electrical harness connector terminal 1 to the Engine Component Power Supply Relay -J757- socket 8 for an open circuit or a short circuit to Ground (GND).

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

-- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

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 appropriate service information.

-- Using a multimeter, check the Fuel Metering Valve -N290- electrical harness connector terminal 2 to the Engine Control Module (ECM) -J623- electrical harness connector T60 terminal 60 for resistance.

Fuel Metering Valve -N290- electrical harness connector terminal	Engine Control Module (ECM) -J623- electrical connector T60 terminal or test box socket
2	60

Specified value: 1.5 Ω Max.

If the specification was not obtained:

-- Check the wiring for an open circuit, a short circuit to each other, Battery (+) or Ground (GND).

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

-- Erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .

-- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to READINESS CODE .

-- End diagnosis.

If the DTC returns and no malfunction is found in the wiring and voltage supply was OK:

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to appropriate service information.

Assembly is performed in the reverse order of the removal, note the following:

Final procedures 

After 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 .