With Integrated Fault-Diagnosis System (Flash Codes): 12221

Diagnostic procedure

A condition for carrying out the work described in the following is that the mass air flow sensor's burn-off function is in working order. If it is not, see "Filament burn-off, checking operation". Testing and Inspection




1 -M1989. Check the voltage level of the signal from the mass air flow sensor with the LH tester or manually by taking readings directly at the connector or with the aid of a Breakout Box.

M1990-. Use an ISAT scan tool. Select command code 22A and check that the following is shown on the ISAT scan tool's display:
- 801.2 1,2 Vat idling speed
- 805.0 5.0 V at wide open throttle.




2 Read off the voltage on the LH tester. It should be 1.2-1.5 Vat idling speed.

Alternatively, take a voltage reading across pins 2 and 3 (pins 3 and 5 for a mass air flow sensor of aluminium).

Alternatively, take a voltage reading across pins 6 and 7 on the Breakout Box.

If the voltage reading obtained is correct, unplug the connector from the mass air flow sensor and check that the power supply and ground connection are Ok. With the ignition switched on, battery voltage should be obtained across pins 1 and 5 (or pins 2 and 4).

If the voltage reading obtained is correct, change the mass air flow sensor.

If it is not, go to point 3.




3 Check the lead between pin 5 of the mass air flow sensor connector (pin 2 for a mass air flow sensor of aluminium) and pin 87B of the main relay. Also check the operation of the relay and the ground lead from pin 1 (or pin 4) to the engine grounding point.




4 Connect the Breakout Box to the car's wiring harness. LH control module connected. Start the engine (idling speed). Take a voltage reading across pins 6 and 7. A reading of 1.2-1.5 V should be obtained.

If the voltage is correct, change the control module.

If the voltage is not correct, unplug the connector from the mass air flow sensor (LH control module not connected). Check the lead between pin 6 of the Breakout Box and pin 2 of the mass air flow sensor connector (pin 3 for a mass air flow sensor of aluminium). Also check the lead between pin 7 of the Breakout Box and pin 3 (or pin 5) of the mass air flow sensor connector.