Faulty Signal

Checking Compression
- Carry out a compression test.
- Is compression OK?

If reading is OK:
^ Proceed to: Checking For Air Leakage In The Intake System section below.

If reading is incorrect:
^ Remedy as necessary.
^ Proceed to: Verification section below.





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.
^ Proceed to: Verification section below.





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.
^ Proceed to: Verification section below.





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

Yes:
^ Try a new rear heated oxygen sensor (HO2S)
^ Proceed to: Verification section below.

No:
^ 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.
- Front and rear heated oxygen sensors connected.
- Engine control module (ECM) connected.
- Start the engine and idle it.
- Go into verification menu.
- Watch EFI-425, wait until the status of EFI-425 switches to tested. This can take up to 15 minutes after the engine has been started.
- Read diagnostic trouble codes (DTCs).
- If EFI-425 is stored it should have intermittent fault status.

If reading is OK:
^ Fault corrected.

If reading is incorrect:
^ 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 Compression section above.