With Integrated Fault-Diagnosis System (Flash Codes): 12224

Diagnostic procedure

1 If an ISAT scan tool is not used, go to point 2.

With the engine hot, select command code 205 on the ISAT scan tool. The display should show the following codes in repeated sequence:

- 8B105 (lean)
- 8B305 (rich)
- 8B005 (inactive)

If any of the codes is shown continuously, the oxygen sensor is not in proper working order.

2 Unplug the single-pole connector from the wiring harness.

Connect the multimeter (2 V d.c. range selected) to the oxygen sensor's black lead and ground. Start the engine. The signal should oscillate between 0 and 1 V, where 0-0.4 V is a lean mixture and 0.6-1.0 V a rich mixture.

Since the signal in question varies with the fuel- air mixture, a lean mixture of the kind caused by a small vacuum leak, for instance, gives an oxygen reading of >1 and a sensor voltage of about 100 mV.

A rich mixture gives an oxygen reading of <1 and a sensor voltage of about 900 mV.

If these readings are not obtained, change the oxygen sensor.

If a signal is present, check the mounting of the oxygen sensor. A poor ground connection due to corrosion could be the cause of malfunctioning.

Connect a 12 V bulb and high power to the oxygen sensor body and battery positive (Batt+). The bulb should light up.

If is does not, remove the oxygen sensor and clean the threads.

With the ignition switch in the OFF position, unplug the oxygen sensor preheater connector and take a resistance reading across the oxygen sensor connections.

The resistance should be 4-8 ohms.

In the event of an open circuit or excessive resistance, change the oxygen sensor.

Useful tip
Run an extra ground lead from the oxygen sensor's outer casing (secured with a hose clip) to engine reference grounding point G7 on the lifting eye.

3 Check that battery voltage is present across the pins in the oxygen sensor connector.

If it is, go to point 4.

If it is not, check
- oxygen sensor fuse 28
- the lead between pin 1 of the oxygen sensor connector and fuse 28.
- the lead between pin 2 of the oxygen sensor connector and ground.

4 Plug the Breakout Box into the car's wiring harness, LH control module not connected. Check the lead between pin 24 of the control module and the oxygen sensor.

5 If the fault persists in spite of the above checks, change the oxygen sensor and check its operation once again by selecting command code 205 on the ISAT scan tool.

6 Try fitting a new control module.