Manufacturer Code Charts: 2079

[1] Check component B28/8 (Pressure differential sensor (DPF)).: Engine protection active due to excessive signal voltage


Possible cause:

- Diesel particulate filter
Affected functions:

- Engine output

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

1. Check component B28/8 (Pressure differential sensor (DPF)).
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 > 0.005 Bar.
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 0.005 Bar?

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

- The picture shows component Exhaust tailpipe.
Figure legend

- AThe exhaust tailpipe is not carbon-fouled.
- BThe 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: Replace component Diesel particulate filter.

1.1. Replace component Diesel particulate filter.
Replace component Diesel particulate filter.
NOTE :Before replacing component Diesel particulate filter, print out the following actual values and include them with the exchanged component.







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: Replace component Diesel particulate filter.

1.1. Replace component Diesel particulate filter.
Replace component Diesel particulate filter.
NOTE :Before replacing component Diesel particulate filter, print out the following actual values and include them with the exchanged component.







Pressing button F2 resets the values in the control unit.

Warning!Communication with ECU required.


NO
Dynamic test B28/8 (Pressure differential sensor (DPF))
The test was not okay.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