Faulty Signal

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

If compression reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Remedy as necessary.





Checking For Air Leakage In The Intake System
- Check for air leakage.
- Is there any air leakage?

No:
^ Proceed to tset step below.

Yes:
^ Remedy as necessary.
^ Then proceed to Verification section below.





Checking For Air Leakage In The Exhaust System
- Check for air leakage.
- Is there any air leakage?

No:
^ Proceed to test step below.

Yes:
^ Remedy as necessary.
^ Then proceed to Verification section below.





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

Yes:
^ Try a new Rear Heated Oxygen Sensor (HO2S).
^ Then proceed to Verification section below.

No:
^ Remedy as necessary.
^ Then 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.
- Start the engine and idle it.
- Go into diagnostic test menu.
- Watch EFI-425, wait until the status of EFI-425 goes over 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 the status intermittent fault.

If reading is OK:
^ Fault corrected

If reading is incorrect:
^ Proceed to test step below.

Fault-tracing Information
- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected

No:
^ Return to Checking Compression section above.