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.
- Is there any air leakage?

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

Yes:
^ Remedy as necessary.
^ Proceed to: Verification section below.





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

Yes:
^ Proceed to: Checking The Rear Heated Oxygen Sensor section below.

No:
^ Remedy as necessary.
^ Proceed to: Verification section below.





Checking The Rear Heated Oxygen Sensor
- Ignition ON.
- Clamp hose between canister purge (CP) valve and intake manifold with a hose clip. 115 8957. An evaporative emission (EVAP) system diagnostic trouble code (DTC) may be stored.
- Go into scrolling values.
- Read off value for rear heated oxygen sensor (HO2S).
- Start engine and idle it until the rear heated oxygen sensor starts operating.
- The rear heated oxygen sensor starts operating just after rear sensor heating starts.
- Remove multi-nipple plugs.
- The voltage across the rear sensor should drop to 0 Volts.
- Wait for approx. 30 seconds, then reinstall plugs on multi-nipple.
- The voltage across the rear sensor should rise to approx. 0.8 Volts.

Yes:
^ Try a new front heated oxygen sensor.
^ Proceed to: Verification section below.

No:
^ Try a new rear heated oxygen sensor.
^ Proceed to: Verification section below.





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

- Ignition OFF.
- Heated oxygen sensor connected.
- Go into diagnostic test menu.
- Test drive car.
- Watch EFI-436, wait until the status of EFI-436 switches to tested.
- Read diagnostic trouble codes.
- If EFI-436 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.