Manufacturer Code Charts: 1345

B2/5 (Hot film mass air flow sensor) : Loose contact with low frequency (P0104)


Possible cause:

- B2/5 (Hot film mass air flow sensor)
Affected functions:

- Engine diagnosis
- Engine output

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Test 1: Check component B2/5 (Hot film mass air flow sensor).

1. Check component B2/5 (Hot film mass air flow sensor).

Test 1.1: Check signal of component B2/5 (Hot film mass air flow sensor) via actual value with engine OFF.

Test 1.2: Check signal of component B2/5 (Hot film mass air flow sensor) via actual value with engine speed greater than 3500 rpm.

Test 1.3: Check power supply of component B2/5 (Hot film mass air flow sensor).

Test 1.4: Check reference signal of component B2/5 (Hot film mass air flow sensor).

1.1. Check signal of component B2/5 (Hot film mass air flow sensor) via actual value with engine OFF.
Warning!Communication with ECU required.


1.2. Check signal of component B2/5 (Hot film mass air flow sensor) via actual value with engine speed greater than 3500 rpm.
Warning!Communication with ECU required.


1.3. Check power supply of component B2/5 (Hot film mass air flow sensor).
Image legends

- B2/5 (Hot film mass air flow sensor)
- Connector (5-pin)
Test prerequisite

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

- Switch off ignition.
- Detach coupling at component B2/5 (Hot film mass air flow sensor).
- Measure direct voltage with multimeter between sockets (B2/5) 2 and (B2/5) 1
- Switch on ignition.
Specified value

- Voltage[11.0...15.0] V
Question

- Is the measurement value OK?







YES
The actual value is okay.Further possible causes of fault

- Unmetered air
- Signal wire
- B2/5 (Hot film mass air flow sensor)
End of test

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

- N10/1f43 (Fuse 43)
- Cable for voltage supply
End of test

1.4. Check reference signal of component B2/5 (Hot film mass air flow sensor).
Test sequence

- Switch on ignition.
Status of relevant actual value:
- HFM-SFI ( Reference signal ):Warning! Communication with ECU required.
Specified value

- Reference signal[46...59] ms
Question

- Is the measurement value OK?


YES
The actual value is okay.End of test

NO
The actual value is not o.k.Possible cause and remedy

- Check lines from component N3/10 (ME-SFI [ME] control unit) to component B2/5 (Hot film mass air flow sensor).
- B2/5 (Hot film mass air flow sensor)