Wastegate: Testing and Inspection

Diagnostic Procedures

Wastegate Bypass Regulator Valve, Checking

Special tools, testers and auxiliary items 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 connections between engine/transmission/chassis OK.

• Ignition switched off.

Test procedure

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

Start diagnosis

- Remove the engine cover with air filter. Refer to the repair information.

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 ohms (at approx. 20° C)

If the specified value was Not obtained:

- Replace the Wastegate Bypass Regulator Valve ( N75). Refer to the repair information.

If the specified value was obtained:

Checking Voltage supply









- Start the engine.

- Using a multimeter, check the Wastegate Bypass Regulator Valve (N75) electrical harness connector terminal 1 to engine ground.

Specified value: Battery voltage.

- Switch the ignition OFF.

If the specified value was Not obtained:

- Check the wiring from the Wastegate Bypass Regulator Valve (N75) to fuse 24 in Fuse Box B for an open, short circuit to each other, high resistance or short to ground.

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

- If necessary, repair the wiring connection.

If the specified value was obtained:

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).

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









Specified value: 1.5 ohms max.

If the specified value was Not obtained:

- Check the wiring for an open or high resistance.

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

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the repair information.

- Install the engine cover with air filter. Refer to the 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 ] Scan Tool Testing and Procedures.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.