WASTEGATE Bypass Regulator Valve, 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 (GND) 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 with air filter.

Checking internal resistance

-- Disconnect the Wastegate Bypass Regulator Valve -N75- electrical harness connector -1-.

-- Using a multimeter, check the Wastegate Bypass Regulator Valve -N75- terminals 1 to 2 for resistance.

Specified value: 20 to 30 Ω (at approx. 20° C)

If the specification was not obtained:

-- Replace the Wastegate Bypass Regulator Valve -N75-. Refer to Turbocharger Recirculation Valve -N249- AND Wastegate Bypass Regulator Valve -N75- .

If the specification is obtained:

Checking Voltage supply

-- Using a multimeter, check the Wastegate Bypass Regulator Valve -N75- electrical harness connector terminal 1 to Ground (GND) for voltage.

Wastegate Bypass Regulator Valve -N75- electrical harness connector terminal	Measure to
1	Engine Ground (GND)

-- Operate the starter briefly.

Specified value: battery voltage.

-- Switch the ignition off.

If the specification was not obtained:

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

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

-- If necessary, repair the wiring connection.

If no malfunction is found in the wiring:

If the manufacturers test box is being used. Perform the following step.

-- Install the Test Box 105 Pin VAG 1598/42.

If the manufacturers test box is not being used. Perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REMOVING AND INSTALLING .

-- Using a multimeter, check the Wastegate Bypass Regulator Valve -N75- electrical harness connector terminal 2 to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminal 4 for resistance.

Wastegate Bypass Regulator Valve -N75- electrical harness connector terminal	Motronic Engine Control Module (ECM) -J623- electrical connector T60 terminal or test box socket
2	4

Specified value: 1.5 Ω max.

If the specification is not obtained:

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

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

If no malfunction is found in 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 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 ENGINE CONTROL MODULE, REMOVING AND INSTALLING .

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 .