Code 12

The AFS measures the intake air volume. It makes use of a Karman Vortex to detect the air flow rate and sends it to the ECU as the intake air volume signal.
The ECU uses this intake air volume signal to decide the basic fuel injection duration.







Circuit Diagram

Troubleshooting Hints

1. If the engine stalls occasionally, crank the engine and shake the AFS harness. If the engine stalls, check for the poor contact of the AFS connector.
2. If the AFS output frequency is other than 0 when the ignition switch is turned on (do not start the engine), Check for the faulty AFS or ECU.
3. If the engine idles even if the AFS output frequency is out of specification, check for the following conditions:

1) Disturbed air flow in the AFS.
2) Poor combustion in the cylinder.
Faulty ignition plug, ignition coil, injector, incorrect compression.
3) Air leaks in the intake manifold.
4) Loose EGR valve seat.







Using Multi-use Tester

NOTE: When the vehicle is new [within intial operation of about 500 km (300 miles)], the air flow sensor output frequency may be about 10% higher.







Harness Inspection Procedure