Upper Limit

Checking Mass Air Flow Sensor
- Ignition ON.
- Connect a voltmeter between mass air flow (MAF) sensor connector terminals 2 and 4.
- The voltmeter should read 0.1 - 0.2 Volts.

If reading is OK:
^ Proceed to: Checking for Air Leakage in the Intake System section below.

If reading is incorrect:
^ Try a new mass air flow sensor.





Checking for Air Leakage in the Intake System
- Check for air leakage.
- Check for air leaks in the intake system.
- Is there any air leakage?

No:
^ Proceed to: Checking for Air Leakage in the Exhaust System section below.

Yes:
^ Remedy as necessary.
^ Continue by erasing diagnostic trouble code (DTC) and resetting long-term fuel trim.





Checking for Air Leakage in the Exhaust System
- Check for air leakage.
- Checking for air leakage in the exhaust system.
- Is there any air leakage?

No:
^ Proceed to: Checking the Fuel and Residual Pressure section below.

Yes:
^ Remedy as necessary.
^ Continue by erasing diagnostic trouble code and resetting long-term fuel trim.





Checking the Fuel and Residual Pressure
- Check fuel and residual pressure.
- Is fuel pressure OK?

Yes:
^ Proceed to: Connecting the Breakout Box section below.

No:
^ Remedy as necessary.
^ Continue with erasing diagnostic trouble codes and resetting adaptive functions.





Connecting the Breakout Box
- Connect the breakout box and check ground terminals.
- Connect engine control module (ECM).
- Check all signals to and from engine control module.
- Remedy as necessary.
- Proceed to: Verification section below.





Verification
After carrying out the repair, check that the fault has been remedied as follows:

- Ignition OFF.
- Reconnect connectors and reinstall components.
- Go into scrolling values.
- Read off the long-term fuel trim value.
- Test drive the car.
- Watch the long-term fuel trim value until it switches to completed.
- If EFI-231/232 are stored they should have intermittent status.

Yes:
^ Fault corrected.

No:
^ Proceed to: Fault-tracing Information section below.

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected.

No:
^ Proceed to: Checking Mass Air Flow Sensor section above.