Test Point 7 - Air flow sensor
TEST POINT 7 - Air flow sensor (V/Ohms) - Fault code 1_21Possible Causes, Elimination, Remarks
Voltage supply (V)
- Disconnect plug at air flow sensor, connect voltmeter to plug terminals 2 and 5 using test leads.
- Turn Ignition on.
Display - approx. 10 - 13.8 Volts
No display: check in accordance with wiring diagram
- Reconnect plug.
Checking the hot-wire signal with System Tester 9288
The air flow sensor signal may be tested directly in the Actual values menu item using System Tester 9288.
- To check the signal, remove upper air cleaner section and start engine.
Display: approx. 2.5 ±O.5 Volts
- Blow against hot wire. This must cause the System Tester display to change.
Checking the hot wire signal (V)
- Connect plug to air flow sensor.
- Pull off Digital Motor Electronics (DME) plug.
- Connect DME plug terminal 36 to ground (e.g. door stop). Connect Voltmeter to DME plug terminal 7 and 26.
Display: approx. 1.4 V
- Blow against air flow sensor and observe voltmeter. A voltage change must occur (approx. 1.6 - 5 V).
Checking the hot-wire burn-off circuit (visual check)
- Operate engine with air flow sensor installed and connected. When an engine temperature > 60° C is reached, increase engine speed to above 2,000 rpm and stop engine (ignition off).
- After a waiting time of approx. 4 seconds, the hot wire must glow for approx. 1 second (burn-off).