P0102

DIAGNOSTIC TROUBLE CODES P0102, P0103
Mass air flow sensor, input to control module, open circuit or shorting to ground/batt+

Fault Symptom.
CHECK ENGINE lamp (MIL) on.
Reluctance to start, poorer DRIVEABILITY and high fuel consumption.

Condition
In the case of a short circuit or open circuit, a diagnostic trouble code will be generated in five seconds.
Air leakage in the induction system or mass air flow sensor.

Diagnostic Procedure.
1. Connect an ISAT scan tool.
Start the engine.
Select "READ FUNCTIONS".
Select "INTAKE AIR MASS".
Check that the Scan Tool shows the following air mass (g/s and V) as a function of engine rpm:
- idling about 0.8 V_____ about 4 g/s
- at 2500 rpm (no load) about 1.2 V _____ about 12 g/s
Slight higher readings will be obtained with a cold engine.

If the readings are OK, proceed to step 5.
If the readings are not OK, continue with step 2.

2. Check the induction system for possible air leakage.





3. Check the electrical interface in the mass airflow sensor's connector.
Unplug the 4-pin connector.
Carry out the following tests with the female connector:

^ with the ignition switch in the ON position, connect the test lamp across:
- pin 1 and Batt+
- pin 2 and Batt+
- pin 3 and batt-
The test lamp should light up.

^ with the engine idling:
- Replace the mass air flow sensor's control module input with a conventional 1.5 V battery in good condition.
- Connect the positive pole of the 1.5 V battery to pin 4.
- Connect the negative pole of the 1.5 V battery to pin 2.
- Connect a Scan Tool.
- Select "READ FUNCTIONS".
- Select "INTAKE AIR MASS".
- Check the operation of the control module, including the wiring harness as far as the mass air flow sensor.
The Scan Tool should show about 1.5 V.

If all readings are OK, check the mass air flow sensor connector for corrosion and possibly remedy it.
If no remedy is possible, fit a new mass air flow sensor.
If any measured value is incorrect, continue with step 4.





4. The mass air flow sensor's electrical connection is faulty.
If the test lamp does not light up there is no connection to ground or no batt+ power supply.
Check the following leads for continuity or a short circuit:
- pin 1 and grounding step G7P.
- pin 2 and crimped connection J130.
- pin 3 and crimped connection J37.

If the Scan Tool does not show about 1.5 V, there is no connection to the control module.
Check the following lead for continuity or a short circuit:
- pin 4 and control module pin 7.
If the measured values are correct, continue with step 5.

5. Clear the diagnostic trouble code and drive the car to see whether the DTC is generated again.

If the diagnostic trouble code is generated again, continue at "Procedure Before ECM Replacement". Component Tests
If the trouble code is not generated again the remedial measure taken was correct, otherwise the fault is of intermittent type.