Fuel Pressure Test

Special tools and workshop equipment required 

• Multimeter.
• Fuel Line Adapter Set VAG 1318 / 17A. These tools may be substituted with an equivalent aftermarket tool and are also available for rental or purchase through Audi.
• In- line fuel pressure gauge with shutoff valve (high pressure).

Test conditions 

• Battery voltage 12.5 V.
• Function and voltage supply for the Fuel Pump is OK.
• Fuel tank at least ¹ /₄ filled.
• Ignition switched off.

Test procedure 

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

Start diagnosis

-- Disconnect the fuel supply line at the supply location and catch any fuel coming out with a shop towel.

-- Install a fuel pressure gauge with appropriate adapters.

-- Open shut off valve on fuel gauge.

-- Switch ignition on and off repeatedly until fuel pressure stops increasing pressure.

-- Read fuel pressure on the gauge.

• Specified value: 3.5 - 6 bar.

If specification is exceeded:

-- Check return line between the fuel filter and the fuel pump for kinks or blockage.

If no malfunction in fuel return line is found:

-- Pressure relief valve in fuel filter is malfunctioning.

-- Replace the fuel filter. Refer to appropriate repair information.

If reading was below the specification:

-- Check fuel pressure at the fuel filter between the fuel pump and the fuel filter using appropriate adapters.

-- Open shut off valve on gauge and start the engine. Allow to idle.

-- Slowly close the pressure gauge, shut off and note the fuel pressure.

• Pressure must increase to 6 bar.

When 6 bar is reached: Open shut off tap immediately!

If pressure has increased during test:

-- Fuel pump is OK. Pressure relief valve in fuel filter is malfunctioning.

-- Replace the fuel filter. Refer to appropriate repair information.

If pressure did not increase:

-- Fuel pump is faulty

-- Replace the fuel pump. Refer to appropriate repair 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 .