118A00

Plausibility error due to defective exhaust gas pressure lines between diesel particulate filter and differential pressure sensor


Possible cause:

- B28/8 (Differential pressure sensor (DPF))
Affected functions:

- Power generation

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Test 1: Check component B28/8 (Pressure differential sensor (DPF)).

1. Check component B28/8 (Pressure differential sensor (DPF)).
Check actual value B28/8 (Pressure differential sensor (DPF)).
Test prerequisite

- Ignition ON
- The air extractor system may not be connected to the exhaust system during the test.
Status of the relevant actual values:
- Coolant temperature:Warning! Communication with ECU required.

- Differential pressure Signal voltage:Warning! Communication with ECU required.
Specified value at coolant temperature between 10 °C and 85 °C

- Differential pressure Signal voltage464...682 mV
Specified value at coolant temperature < 10 °C or > 85 °C

- Differential pressure Signal voltage428...718 mV
Question

- Is the actual value o.k.?


YES
Check component B28/8 (Differential pressure sensor (DPF)) using actual value.
Test sequence

- Engine at idle
- In the event of a throttle blip, the actual value of component B28/8 (Differential pressure sensor (DPF)) must change by > 5 hPa.
Status of relevant actual value:
- B28/8 (Pressure differential sensor (DPF)):Warning! Communication with ECU required.
Question:Does the actual value change by more than 5 hPa?

YES
Check exhaust tailpipe for carbon fouling.
The test was okay.Note

- The picture shows component Exhaust tailpipe.
Figure legend

- A The exhaust tailpipe is not carbon-fouled.
- B The exhaust tailpipe is carbon-fouled.
Question:Is the exhaust tailpipe carbon-fouled?







YES
The exhaust tailpipe is carbon-fouled.Remedy

- The diesel particulate filter is not installed or damaged.
- Replace component Diesel particulate filter.
Continue with button F2

Test 1.1: Teach-in process after replacement of component Diesel particulate filter

1.1. Teach-in process after replacement of component Diesel particulate filter
Note

- Before replacing component Diesel particulate filter, print out the following actual values and include them with the exchanged component.
Preconditions

- Engine running








Pressing button F2 resets the values in the control unit.

Warning!Communication with ECU required.


NO
The exhaust tailpipe is not carbon-fouled.The ash content of the diesel particulate filter is too high.Remedy

- Replace component Diesel particulate filter.
Continue with button F2

Test 1.1: Teach-in process after replacement of component Diesel particulate filter

1.1. Teach-in process after replacement of component Diesel particulate filter
Note

- Before replacing component Diesel particulate filter, print out the following actual values and include them with the exchanged component.
Preconditions

- Engine running








Pressing button F2 resets the values in the control unit.

Warning!Communication with ECU required.


NO
Dynamic test B28/8 (Pressure differential sensor (DPF))
Figure legend

- 1Exhaust gas pressure line upstream of diesel particulate filter
- 2Exhaust gas pressure line downstream of diesel particulate filter
- 019Vacuum tester
- B28/8 (Pressure differential sensor (DPF))
Test sequence

- Switch off ignition.
- Connect vacuum tester to exhaust gas pressure line upstream of diesel particulate filter.(See fig.)
- Using vacuum tester, set a positive pressure of 300 hPa.
- Switch on ignition.
Communication with ECU required







NO
Check power supply of component B28/8 (Pressure differential sensor (DPF)).
Figure legend

- B28/8 (Pressure differential sensor (DPF))
Special tool

- Adapter cable611 589 03 63 00
Test prerequisite

- The actual value is not o.k.
Test prerequisite

- Switch off ignition.
- Detach coupling at component B28/8 (Pressure differential sensor (DPF)).
- Connect adapter cable no. 611 589 03 63 00 to engine wiring harness B28/8 (Pressure differential sensor (DPF)).
- Measure direct voltage with multimeter between sockets (B28/8x1) 2 and (B28/8x1) 3
- Switch on ignition.
Specified value

- Voltage[4.9...5.2]V
Question

- Is the measurement value OK?







YES
Check signal lines on component B28/8 (Pressure differential sensor (DPF)).
Figure legend

- B28/8 (Pressure differential sensor (DPF))
Special tools

- Test cable 266 589 01 63 00
- Socket box 129 589 00 21 00
- Adapter cable611 589 03 63 00
Test sequence

- Switch off ignition.
- Unplug connector of control module and component.
- Connect 126-pole socket box at engine wiring harness.
- Measure resistance with multimeter between socket (M.31) 31 of the 126-pole socket box tester and socket (B28/8x1) 1
Specified value

- Resistor<1ohms
Question

- Is the measurement value OK?







YES
The measurement value is OK.Remedy

- Replace component B28/8 (Pressure differential sensor (DPF)).
Note

- Initialization is necessary after exchanging component 'B28/8 (Pressure differential sensor (DPF))'.
End of test

NO
The measurement value is not OK.Remedy

- Test signal line between components CDI6 and B28/8 (Pressure differential sensor (DPF)) for Open circuit.
End of test

NO
The measurement value is not OK.Remedy

- Check voltage supply lines of component B28/8 (Pressure differential sensor (DPF)) as per wiring diagram.
End of test