P0102

DIAGNOSTIC TROUBLE CODES PO1O2, PO1O3
Mass air flow sensor, input to control module low/high, no continuity or shorting to ground/batt+.

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

Condition
Air flow less than about 0.8 grammes per second at engine speeds above 520 rpm or greater than about 165 grammes per second at engine speeds below 6520 rpm.

Diagnostic Procedure.
1. With the ISAT command "INDUCTION AIR MASS" in the "READ FUNCTIONS" menu, check that the following readings can be obtained on the display:
- approx. 4 gram/s-approx. 0.8 V-idling
- approx. 10 gram/s-approx. 1.2 V-2500 rpm (no load)
- approx. 130 gram/s-approx. 3.9 V-full throttle (no load)

2. Check the induction system for leakage.
3. Check that pin 1 of the mass air flow sensor is properly grounded. If it is not, check the lead between pin 1 and grounding point G7P.





4. With the ignition switch in the Drive position, check that battery voltage is present on pin 3 of the mass air flow sensor.

If it is not, check the lead between pin 3 and pin 87 of the main relay.

5. With the ignition switch in the DRIVE position, check that pin 2 of the mass air flow sensor is properly grounded.

If it is not, check the lead between pin 2 and pin 30 of the control module.

6. With the ignition switched off, connect a BOB between the MOTRONIC control module and the wiring.

Start the engine and check that current is present on pin 7 of the control module, as follows:
- approx. 0.8 V when idling
- approx. 1.2 V at 2500 rpm (no load)
- approx. 3.9 V at full throttle (no load)

The above voltages may vary somewhat, depending on engine temperature, current consumption, etc. Should the mass air flow sensor be defective, the differences in the readings obtained will probably be fairly wide. In such case, change the mass air flow sensor.

7. If no fault has been detected after carrying out the above checking procedure, clear any diagnostic trouble codes, drive the car on the road and check whether the trouble code is generated afresh.
8. If the fault still persists, continue at "Before Control Module Replacement" for further diagnostic instructions. Before Replacing A Control Module