P20E2

Boost pressure too high

Test 1: Check system 'Charge pressure control'.

1. Check system 'Charge pressure control'.

Test 1.1: Actual value is less than the specified value

Test 1.2: Actual value is greater than the specified value

1.1. Actual value is less than the specified value

Test 1.1.1: Inspect charge air system for leaks.

Test 1.1.2: Check system 'Charge pressure control'.

Test 1.1.3: Check divert air system.

1.1.1. Inspect charge air system for leaks.
Inspect charge air system for leaks.Possible cause and remedy

- Check charge air system for leaks and tighten all hose clamps (see diagram).
- Check for unrestricted flow in charge air system.
Note

- If no boost pressure is built up, it may be because the turbocharger is not functioning (blocked).In this case, remove the exhaust system and check for free movement of both turbochargers by hand.
Figure legend/figure

- 5/1-Charge air cooler, left cylinder bank
- 5/2-Charge air cooler, right cylinder bank
- 12- Intake manifold
- 110a-Left turbocharger
- 110b-Right turbocharger
- 110/1-Suction pipe
- 110/6-Boost pressure pipe
- 121/1-Air cleaner, left cylinder bank
- 121/2-Air cleaner, right cylinder bank
- 110/7-Hose section with hose clamp
- 101/8-Y-connection
- M16/6 (Throttle valve actuator)
B- ExhaustD- Clean air downstream of air cleanerE- Charge air













1.1.2. Check system 'Charge pressure control'.
Figure legend/figure

- 019 -Overpressure-Vacuum tester
- a -Hose connection to component Y31/5 (Charge pressure control vacuum transducer)
- b -Hose to component 'Y31/5 (Charge pressure control vacuum transducer)'
Test sequence

- Switch off ignition.
- Remove components Covering at engine and Lower engine compartment paneling.
- Detach hose a to component Y31/5 (Charge pressure control vacuum transducer) at component 'Charge air cooler, right cylinder bank' and connect pressure/vacuum tester to hose b.
- Apply pressure to the vacuum cells for the boost pressure control valve with a pressure of approx. 800 mbar set on the pressure tester.
- Hold pressure.
Specified value

- Pressure may drop by no more than 50 over 1 min.
Question

- Is the pressure maintained?







YES
Figure legend/figure

- 110bRight turbocharger
- 110/3bControl rod
Test sequence

- Check whether control rod [110/3b] from the vacuum cell to the boost pressure control valve (left and right cylinder bank) is extended by 8 - 13 mm.
Question

- Is the test o.k?







YES
Test sequence

- Use pressure tester to adjust pressure to approx. 800 mbar.
- Switch on ignition.
- Briefly actuate component Y31/5 (Charge pressure control vacuum transducer).
- Bridge between sockets [3.4] 37 and [2.23] 32 of the 126-pole socket box tester.
Specified value

- Overpressure< 400 mbar
Question

- Is the pressure achieved?







YES
The test is o.k..End of test

NO
The test is not o.k..Possible cause and remedy

- Y31/5 (Charge pressure control vacuum transducer)
- Left or right vacuum cell
End of test

NO
The test is not o.k..Possible cause and remedy

- Control rod is bent
- Boost pressure control valve is stuck (stays open).
End of test

NO
The test is not o.k..Possible cause and remedy

- Hose to component 'Y31/5 (Charge pressure control vacuum transducer)'
- Hose from component Left or right vacuum cell to component Y31/5 (Charge pressure control vacuum transducer)
- Left or right vacuum cell
- Y31/5 (Charge pressure control vacuum transducer)
End of test

1.1.3. Check divert air system.
Figure legend/figure

- 019 -Overpressure-Vacuum tester
- B -Test connection for deceleration air system
Test sequence

- Switch off ignition.
- Connect vacuum tester to test connection B.
- Use the vacuum tester to set a vacuum of approx. 700 mbar.
- Hold pressure.
Specified value

- With the system leaktight, the pressure may drop by no more than 50 mbar over 1 min.
Question

- Is the pressure maintained?







YES
Figure legend/figure

- 019 -Overpressure-Vacuum tester
- B -Test connection for deceleration air system
Test sequence

- Connect vacuum tester to test connection B.
- Use the vacuum tester to set a vacuum of approx. 700 mbar.
- Actuate component Y101 (Divert air switchover valve), then with key F2.
Specified value

- Vacuum drops by at least 60 mbar and remains constant.
Proceed to 'Actuation' with F2







Warning!Communication with ECU required.

NO
The test was not okay.Possible cause and remedy

- Vacuum line to vacuum tank
- Vacuum line from vacuum tank to component Y101 (Divert air switchover valve)
- Vacuum reservoir
End of test

1.2. Actual value is greater than the specified value

Test 1.2.1: Check system 'Charge pressure control'.

1.2.1. Check system 'Charge pressure control'.
Figure legend/figure

- 019 -Overpressure-Vacuum tester
- a -Hose connection to component Y31/5 (Charge pressure control vacuum transducer)
- b -Hose to component 'Y31/5 (Charge pressure control vacuum transducer)'
Test sequence

- Switch off ignition.
- Remove components Covering at engine and Lower engine compartment paneling.
- Detach hose a to component Y31/5 (Charge pressure control vacuum transducer) at component 'Charge air cooler, right cylinder bank' and connect pressure/vacuum tester to hose b.
- Apply pressure to the vacuum cells for the boost pressure control valve with a pressure of approx. 800 mbar set on the pressure tester.
Specified value

- With the system leaktight, the pressure may drop by no more than 50 mbar over 1 min.
Question

- Is the pressure maintained?







YES
Figure legend/figure

- 110bRight turbocharger
- 110/3bControl rod
Test sequence

- Check whether control rod [110/3b] from the vacuum cell to the boost pressure control valve (left and right cylinder bank) is extended by 8 - 13 mm.
Question

- Is the test o.k?







YES
Test sequence

- Use pressure tester to adjust pressure to approx. 800 mbar.
- Switch on ignition.
- Briefly actuate component Y31/5 (Charge pressure control vacuum transducer).
- Bridge between sockets [3.4] 37 and [2.23] 32 of the 126-pole socket box tester.
Specified value

- Overpressure< 400 mbar
Question

- Is the pressure achieved?







YES
The test is o.k..End of test

NO
The test is not o.k..Possible cause and remedy

- Y31/5 (Charge pressure control vacuum transducer)
- Left or right vacuum cell
End of test

NO
The test is not o.k..Possible cause and remedy

- Control rod is bent
- Boost pressure control valve is stuck (stays closed).
- Hose from component Left or right vacuum cell to component Y31/5 (Charge pressure control vacuum transducer) is pinched
End of test

NO
The test is not o.k..Possible cause and remedy

- Hose to component 'Y31/5 (Charge pressure control vacuum transducer)'
- Hose from component Left or right vacuum cell to component Y31/5 (Charge pressure control vacuum transducer)
- Left or right vacuum cell
- Y31/5 (Charge pressure control vacuum transducer)
End of test