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Home >> Mercedes Benz >> 2012 >> S 400 (221.195) V6-3.5L (272.974) Hybrid >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0072

P0072


The outside temperature sensor has a short circuit to ground.


Possible cause:

- B14 (Ambient temperature display temperature sensor)
- B2/5b1 (Intake air temperature sensor)
Affected functions:

- Engine output

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Test 1: Check component B2/5b1 (Intake air temperature sensor).

Test 2: Check component B14 (Ambient temperature display temperature sensor).

1. Check component B2/5b1 (Intake air temperature sensor).

Test 1.1: Check component B2/5b1 (Intake air temperature sensor) using actual value.

Test 1.2: Check plausibility of actual value B2/5b1 (Intake air temperature sensor) in control module ME 177.

Test 1.3: Check internal resistance of component B2/5b1 (Intake air temperature sensor).

1.1. Check component B2/5b1 (Intake air temperature sensor) using actual value.
Test sequence

- Switch on ignition.
Status of relevant actual value:
- Intake air temperature:Warning! Communication with ECU required.
Specified value

- Current temperature in area surrounding component B2/5b1 (Intake air temperature sensor)
Question

- Is the actual value o.k.?


YES
The actual value is okay.End of test

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

- Check plausibility of actual value B2/5b1 (Intake air temperature sensor) in control module N3/10 (ME-SFI [ME] control unit).
- Check internal resistance of component B2/5b1 (Intake air temperature sensor).


1.2. Check plausibility of actual value B2/5b1 (Intake air temperature sensor) in control module ME 177.
Image legends

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

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

- Detach coupling at component B2/5 (Hot film mass air flow sensor).
- Switch on ignition.
Status of relevant actual value:
- Intake air temperature:Warning! Communication with ECU required.
Specified value

- If the connector is unplugged at component B2/5b1 (Intake air temperature sensor), value [ -40° C ] is displayed.
- Bridge pin 2 in pin 3 at the unplugged connection of component B2/5b1 (Intake air temperature sensor).The value is approx. [ 150° C ] for a short period of time and drops back down to the substitute value of approx. [ 40° C ].
Question

- Is the actual value o.k.?







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

- Check internal resistance of component B2/5b1 (Intake air temperature sensor).


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

- Signal wire
End of test

1.3. Check internal resistance of component B2/5b1 (Intake air temperature sensor).
Test sequence

- Switch off ignition.
- Detach coupling at component B2/5 (Hot film mass air flow sensor).
- Measure resistance with multimeter between pins (B2/5) 2 and (B2/5) 3
Specified value

- Resistor(20° C): [2350...2500]ohms
- Resistor(30° C): [1600...1700]ohms
- Resistor(40° C): [1100...1200]ohms
- Resistor(50° C): [800...900]ohms
Question

- Are the measurement values OK?







YES
The measurement values are OK.End of test

NO
The measurement values are not OK.Possible cause and remedy

- B2/5b1 (Intake air temperature sensor)
End of test

2. Check component B14 (Ambient temperature display temperature sensor).

Test 2.1: Check component B14 (Ambient temperature display temperature sensor).

2.1. Check component B14 (Ambient temperature display temperature sensor).
Test prerequisites

- The power supply of component N10/1 (Front SAM control unit with fuse and relay module) is OK.
- Fault code 9103 is current, and (or) at least one of the relevant actual values is not OK.
Status of relevant actual value:
- B14 (Ambient temperature display temperature sensor):Warning! Communication with ECU required.
Test sequence

- Detach coupling at component B14 (Ambient temperature display temperature sensor).
- Connect resistance simulator to the connector of component B14 (Ambient temperature display temperature sensor).
- Connect resistance substitution unit between sockets (B14)1 and (B14) 2
- Adjust resistance values one after another and compare them with the actual value.
Specified value

- Resistor9.6 kohms:Temperature: [0° C]
- Resistor5.9 kohms:Temperature: [10° C]
- Resistor3.7 kohms:Temperature: [20° C]
- Resistor2.4 kohms:Temperature: [30° C]
- Resistor1.6 kohms:Temperature: [40° C]
Question:Is the actual value o.k.?







YES
The actual value is okay.Possible cause and remedy

- Component B14 (Ambient temperature display temperature sensor) is defective.
End of test







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

- Test cable from control module N10/1 (Front SAM control unit with fuse and relay module) (connector MR7, pin 26) to component B14 (Ambient temperature display temperature sensor) (connector 1, pin 1).
- Test cable from control module N10/1 (Front SAM control unit with fuse and relay module) (connector MR7, pin 18) to component B14 (Ambient temperature display temperature sensor) (connector 1, pin 2).
- Inspect cables, connectors, plug connections, fuses and electrical components for signs of damage, correct connection, loose contact, corrosion etc.
- Component N10/1 (Front SAM control unit with fuse and relay module) is defective.
Note:Connector assignments with key F7End of test













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