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RIP
RIP, Lead Techinician
Category: Mercedes
Satisfied Customers: 5591
Experience:  Mercedes Aftermarket Training, ASE Master Technician, Adv. Engine Performance 10 years
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2004 230 Komp with a check end light P0237, Turbo/super ...

Resolved Question:

2004 230 Komp with a check engine light P0237, Turbo/super charger boost sensor A CKT low input. Any ideas? Checked with the SDS system.
Submitted: 6 years ago.
Category: Mercedes
Expert:  RIP replied 6 years ago.

Hi, welcome to Just Answer.

Below is the complete factory procedure to diagnose this code. There are various reasons it will set, but the most common is a faulty boost pressure sensor or a leak in the charge plumbing. Often someone has worked on the engine and left clamps loose or not completely reinstalled the ducts. The best method to check leaks is with the use of smoke machine. Also check the vacuum hoses, which deteriorate and cause the recirculating flap actuator to become inoperative.

P0237
otes

[1] Charge pressure is too low. [P0237]

Charge pressure is too low.

Test 1:Inspect charge air system for leaks
Test 2:Adaptation M16/7 (Recirculating air flap actuator)
Test 3:Check component B28 (Pressure sensor)
Test 4:Check correct assignment of compressor

1 Inspect charge air system for leaks

Special tool

  • Test pressure gauge Charge air 611 589 02 21 00
  • Connection adapter 271 589 00 91 00

Figure legend

graphic

  • 119 Test pressure gauge
  • 119/3 Compressed-air line
  • 119/4 Plug 'Oil dipstick'
  • 119/6 Connection adapter

Test sequence

  • Remove air cleaner element.
  • Seal guide tube for oil dipstick with stop plug.

Safety note!!:

  • Only remove or install the plug when the charge air system is pressureless!
  • Connect test pressure gauge. (See fig.)
  • Open shutoff cock of tester in direction of flow.
  • Turn pressure reducing valve knob SLOWLY to the right until 300 mbar is reached.

IMPORTANT NOTE

  • The pressure in the system will build up quite SLOWLY .

Leaks can now be located acoustically or made visible by spraying on leak detector spray.

Question: Was the test o.k.?

No

  • The test is not o.k..

Fig. legend/ fig.

graphic

  • b Air line Secondary air system
  • B2/5 (Hot film MAF sensor)
  • M16/6 (throttle valve actuator)
  • M16/7 (Recirculating air flap actuator)
  • 122 Suction damper
  • 50 Kompressor
  • Pressure damper
  • 110/1 Suction pipe
  • 110/2 Charge air cooler
  • 110/6 Suction/charge line

Possible cause and remedy

  • Inspect all the vacuum lines connected to the inlet tract, for leaks and damage, and replace if necessary.

**End of test**

Yes

  • The test is o.k..

**End of test**

2 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**

3 Check component B28 (Pressure sensor)

Test 3a:Check actual value B28 (Pressure sensor)
Test 3b:Test voltage supply of component B28 (Pressure sensor)
Test 3c:Test signal voltage of component B28 (Pressure sensor)

3a Check actual value B28 (Pressure sensor)

Test prerequisite

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.?

3b 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**

3c Test signal voltage of component B28 (Pressure sensor)

Figure legend
graphic

  • 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**

    4 Check correct assignment of compressor

    Possible cause and remedy:

    • Inspect belt pulley for color and diameter.

    Engine version: 1 105/120SW

    • Engine: 271.940, 271.941, 271.942, 271.943, 271.944, 271.945, 271.946, 271.947
    • Color: White marking
    • Diameter: 72 mm

    Engine version: 2 140SW

    • Engine: 271.948 271.949
    • Color: Green marking
    • Diameter: 66 mm **End of test**

     

 

Let me know if you run into any other questions.....
RIP, Lead Techinician
Category: Mercedes
Satisfied Customers: 5591
Experience: Mercedes Aftermarket Training, ASE Master Technician, Adv. Engine Performance 10 years
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