P0101

P0101 00

Mass Air Flow Sensor Malfunction (Variation From Calculated Air Mass)







Fault symptom
- Check Engine (OBDII, EOBD).
- Cruise control not working.
- Limp home
- Possible driveability problem.

On-board diagnosis

Type of diagnosis:
- Continuous

Enable criteria:
- Battery voltage must be between 11 - 16 V.
- Vehicle speed above 30 km/h for more than 60 s accumulated time.
- Coolant temperature between 71 degree C and 115 degree C.
- Engine speed between 1400 and 4000 rpm.
- No fuel shut-off.
- Air mass 7 - 20 g/s.

Fault criteria:
- Conditions for test 1, 2, 3 or 4 are fulfilled.

Test 1
- The mass air flow sensor shows a value 12% lower than the calculated one while multiplicative adaptation is greater than 17%.

Test 2
- The mass air flow sensor shows a value 12% higher than the calculated one while multiplicative adaptation is less than -17%.
Test 3
- The mass air flow sensor shows a value 30% lower than the calculated one.

Test 4
- The mass air flow sensor shows a value 30% higher than the calculated one.

Dependent:
P0107, P0108
P0112, P0113
P0237, P0238

System reaction to a fault:
- The system continues to function with a calculated air mass instead of the value from the mass air flow sensor.
- Boost pressure adaption is blocked and reset.
- Limited acceleration and idle function.
- Cruise control blocked.
- Secondary air pump not active, if fitted.

OK report:
- Diagnosis completed without fault report.

Fault handling:
Type III
(See section Fault handling III, "Other emission-related components and functions" for more information.)

Checking the wiring harness
- Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.

Diagnostic help

Diagnosis regards:
- The DTC indicates that the value from the mass air flow sensor has been deemed unreliable after comparison with a calculated value. This could be due to an air leak or a faulty mass air flow sensor.
- The air mass signal is compared to a calculated value under light, normal and continuous engine loads. The calculated value is derived from the pressures given by the pressure sensors in the intake system.
- First check the integrity of the intake system. Then continue with fault diagnosis.
- If DTC P0171 or P0172 is stored, it is cleared by P0101.

Functions in the diagnostic tool related to the fault:

Test value:
- Air Mass
- Airmass / Combustion
- Airmass / Combustion Calculated
(See also description of readings/activations in diagnostic tool)