Operation CHARM: Car repair manuals for everyone.

P0238



[2] Charge pressure is too high. [P0238]

Test 1: Check component B28 (Pressure sensor)
Test 2: Check component B18 (Altitude pressure sensor)
Test 3: Adaptation M16/7 (Recirculating air flap actuator)
Test 4: Check exhaust back pressure

1 Check component B28 (Pressure sensor)

Test 1a: Check actual value B28 (Pressure sensor)
Test 1b: Test voltage supply of component B28 (Pressure sensor)
Test 1c: Test signal voltage of component B28 (Pressure sensor)

1a Check actual value B28 (Pressure sensor)

Test prerequisite
- Coolant temperature > 80°C

Test sequence
- Engine at idle speed

Status of relevant actual value:
- Temperature of coolant: Communication with ECU required
- Intake manifold pressure: Communication with ECU required
- Altitude pressure: Communication with ECU required

Specified value
- Intake manifold pressure ca. [250 ... 400] hPa
- Altitude pressure ca. [950 ... 1100] hPa

Question: Is the actual value o.k.?

1b Test voltage supply of component B28 (Pressure sensor)

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

Test sequence
- Switch off ignition.
- Connect test wiring harness with socket box to component N3/10 (ME-SFI control module).
- [M.57] 57<-->68 [M.68]
- Switch on ignition

Specified value
- Voltage [4.8 ... 5.2] V

Question: Is the measured value okay?

No
- The measured value is not o.k.
Possible cause and remedy
- Cable for voltage supply
- N3/10 (ME-SFI control module)
**End of test**

Yes
- The measured value is o.k.
Possible cause and remedy
- Signal wire
- B28 (Pressure sensor)
**End of test**

1c Test signal voltage of component B28 (Pressure sensor)

Figure legend
- 019 Vacuum tester

Test prerequisite
- The voltage supply of the component B28 (Pressure sensor) is o.k.

Test sequence
- Switch off ignition.
- Connect vacuum tester to intake manifold using 3-way distributor.
- Connect test wiring harness with socket box to component N3/10 (ME-SFI control module).
- [M.33] 33<-->27 [M.27]

Specified values
- Ignition ON: > 3.5 V
- Operate engine at idling speed.(Vacuum> 500 mbar): < 2 V

Question: Are the measured values okay?

No
- The measured values are not o.k.
Possible cause and remedy
- Leads to component B28 (Pressure sensor)
- B28 (Pressure sensor)
Further possible causes of fault
- Vacuum line
**End of test**

Yes
- The measured values are o.k.
**End of test**

2 Check component B18 (Altitude pressure sensor)

Test 2a: Check actual value B18 (Altitude pressure sensor)
Test 2b: Test voltage supply of component B18 (Altitude pressure sensor)

2a Check actual value B18 (Altitude pressure sensor)

Test sequence
- Switch on ignition.

Status of relevant actual value:
- Atmospheric pressure: Communication with ECU required

Specified value
- Atmospheric pressure [950 ... 1100] hPa

Note: The atmospheric pressure is 950 to 1100 mbar (the pressure may be lower in high mountainous regions). (1mbar = 1hPa)

Question: Is the actual value o.k.?

2b Test voltage supply of component B18 (Altitude pressure sensor)
Fig. legend/ fig.

Picture 1
1 - ConnectorB18 (Altitude pressure sensor)
2 - Securing bolts B18 (Altitude pressure sensor)
B18 - B18 (Altitude pressure sensor)

Picture 2





Connector assignment B18 (Altitude pressure sensor)

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

Test sequence
- Switch off ignition.
- Detach the socket at the component B18 (Altitude pressure sensor).
- (B18) 1<-->3 (B18)
- Connect 126 und 35-pole socket box between engine wiring harness and control module N3/10 (ME-SFI control module).
- [M.57] 57<-->68 [M.68]
- Switch on ignition.

Specified value
- Voltage [4.8 ... 5.2] V

Question: Is the measured value okay?

No
- The measured value is not o.k.
Possible cause and remedy
- Cable for voltage supply
- N3/10 (ME-SFI control module)
**End of test**

Yes
- The measured value is o.k.
Possible cause and remedy
- Signal wire
- B18 (Altitude pressure sensor)
**End of test**

3 Adaptation M16/7 (Recirculating air flap actuator)

Possible cause and remedy
- Mechanical fault,Inspect intake tract for residues.
- Test cables
- N3/10 (ME-SFI control module)

**End of test**

4 Check exhaust back pressure

Note: No further information available