20B7

B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank)


Possible cause:

- B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank)
Affected functions:

- Engine output

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Test 1: Check component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).

1. Check component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).
Note

- Components B28/4. B28/5. B28/6. and B28/7 are identical in design and differentiated by a colored marking.
ComponentB28/4 (Pressure sensor downstream of air cleaner, left cylinder bank)/B28/5 (Pressure sensor downstream of air cleaner, right cylinder bank)

- Marking 'Green'
ComponentB28/6 (Pressure sensor upstream of throttle valve)/B28/7 (Pressure sensor downstream of throttle valve)

- Marking 'Blue'
Continue with button F2

Test 1.1: Check component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank) using actual value.

Test 1.2: Check power supply of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).

Test 1.3: Test signal voltage of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).

1.1. Check component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank) using actual value.
Warning!Communication with ECU required.


1.2. Check power supply of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).
Test prerequisite

- The actual value is not o.k.
- The power supply of component N3/10 (ME-SFI [ME] control unit) is OK.
Test sequence

- Switch off ignition.
- Detach coupling at component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).
- Measure direct voltage with multimeter between sockets (B28/4) 1 and (B28/4) 3
- Switch on ignition.
Specified value

- Voltage 4.75...5.25 V
Question

- Is the measurement value OK?


YES
The measurement value is OK.Further possible causes of fault

- Test signal voltage of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).
End of test

NO
The measurement value is not OK.Possible cause and remedy

- Lines to component N3/10 (ME-SFI [ME] control unit)
- N3/10 (ME-SFI [ME] control unit)
End of test

1.3. Test signal voltage of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank).
Test prerequisite

- The power supply of component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank) is OK.
Test sequence

- Switch off ignition.
- Connect socket box (126-pin) to component N3/10 (ME-SFI [ME] control unit).
- Measure direct voltage with multimeter between sockets (3.4) 37 and (3.23) 56 of the 126-pole socket box tester.
- Switch on ignition.
Specified values

- Voltage3.5...4.0 V
Question

- Are the measurement values OK?


YES
The measurement values are OK.End of test

NO
The measurement values are not OK.Possible cause and remedy

- Lines to component B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank)
- B28/4 (Pressure sensor downstream of air cleaner, left cylinder bank)
Further possible causes of fault

- Air cleaner dirty
End of test