Sub Oxygen Sensor (California Only)

1. Check the sub oxygen sensor only if CODE 27 is indicated by self-diagnostic test.
2. Cancel CODE 27, (Refer to procedure).
3. Start engine and warm-up to normal operating temperature.
4. Drive vehicle for five minutes or more in drive range. Do not exceed 50 mph.
5. Fully depress accelerator pedal for 2 seconds. Stop vehicle and turn ignition switch OFF.
6. Repeat steps 3 - 5.
7. If CODE 27 resets, check sub oxygen sensor wiring circuit for shorts or opens.
8. If no problems are found, replace sub oxygen sensor.


OXYGEN SENSOR HEATER

Fig. 42 Testing Oxygen Sensor Heater Resistance:

1. Engine and oxygen sensor must be cold, 68°F or less.
2. Disconnect the oxygen sensor from electrical connector.
3. Using an ohmmeter, measure the resistance between terminals +B and HT. Fig. 42
4. The OS heater resistance should be 5.1 - 6.3 Ohms.
5. If not as specified, replace the oxygen sensor.