The exhaust oxygen sensor or O 2 S, is mounted in the exhaust stream where it monitors oxygen content in the exhaust gas. The oxygen content in the exhaust is a measure of the air/fuel mixture going into the engine. The oxygen in the exhaust reacts with the oxygen sensor to produce a voltage which is read by the ECM.
There are two types of oxygen sensors used in these vehicles. They are the single wire oxygen sensor (O 2 S) and the heated oxygen sensor (HO 2 S). The oxygen sensor is a spark plug shaped device that is screwed into the exhaust manifold. It monitors the oxygen content of the exhaust gases and sends a voltage signal to the Electronic Control Module (ECM). The ECM monitors this voltage and, depending on the value of the received signal, issues a command to the mixture control solenoid on the throttle body to adjust for rich or lean conditions.
The heated oxygen sensor has a heating element incorporated into the sensor to aid in the warm up to the proper operating temperature and to maintain that temperature.
The proper operation of the oxygen sensor depends upon four basic conditions:
Removal & Installation
The oxygen sensor can be located in several places. Either in the exhaust manifold, front pipe or catalytic converter.
- The best condition in which to remove the sensor is when the engine is moderately warm. This is generally achieved after two to five minutes (depending on outside temperature) of running after a cold start. The exhaust manifold has developed enough heat to expand and make the removal easier but is not so hot that it has become untouchable. Wearing heat resistant gloves is highly recommended during this repair.
- With the ignition OFF , unplug the connector for the sensor.
- Remove the two sensor attaching bolts.
- Remove the oxygen sensor from its mounting place and discard the gasket.
A special socket is available to remove the sensor.
During and after the removal, use great care to protect the tip of the sensor if it is to be reused. Do NOT allow it to come in contact with fluids or dirt. Do NOT attempt to clean it or wash it.
- Apply a coat of anti-seize compound to the bolt threads but DO NOT allow any to get on the tip of the sensor.
- Position a new gasket, install and secure the sensor.
- Reattach the electrical wiring and insure a clean, tight connection.
2.2L (5S-FE) VIN G
- Disconnect the oxygen sensor connector.
- Using an ohmmeter, measure the resistance between the terminals +B and HT. Resistance specification: 11 - 16 ohms at 20°C (68°F).
- If the resistance is not as specified, replace the sensor.
Reconnect the oxygen sensor connector.
Use an analog voltmeter or a digital voltmeter with an analog function to perform this test.
- Start the engine and bring it to normal operating temperature, then run the engine above 2500 rpm for 90 seconds or more.
- Connect the voltmeter between terminals TE1 and E1 of the DLC1 and maintain the engine speed of 2500 rpms.
- Record the number of times the voltmeter fluctuates in 10 seconds.
- If the needle fluctuates eight times or more the oxygen sensor is functioning properly.
- If the needle fluctuates less than eight times in 10 seconds, check that the engine rpm is still 2500 and repeat the test.
- If the needle still fluctuates less than eight times, disconnect the terminals TE1 and E1 of the DLC1 and maintain the engine speed at 2500 rpm.
- Measure the voltage between terminals VF1 and E1 . If the voltage is more than zero volts, replace the sensor.