During handling of the oxygen sensor, do not hit the end of the sensor. The sensor can be easily damaged by impact or rough handling. Additionally, do not allow the sensor to come in contact with water or petroleum products.
The exhaust oxygen sensor or O2S, 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 ECU.
Testing With a Voltmeter
- Make sure the following conditions prevail before checking the oxygen sensor:
- Air cleaner installed.
- Engine has reached normal operating temperature.
- All pipes and hoses of the air intake system are connected.
- All accessories are switched off.
- Electronic fuel injection (EFI) wiring connections tightly connected.
- Ignition timing correct.
- Transmission in Neutral, parking brake set and wheels blocked.
- Connect a suitable tachometer to the engine, always connect the positive terminal of the tachometer to the engine service connector (IG terminal) located under in the engine compartment. Using a suitable piece of jumper wire short the terminals of the check engine connector (1983-88 T and E1 1989-90 TE1 and E1), located in the engine compartment.
- Connect a voltmeter to the Vf and E1 (Vf1 1989-90) terminals of the engine (diagnosis) service connector, located in the engine compartment.
- Warm up the oxygen sensor with the engine at running at 2500 rpm for approximately 2 minutes.
- Maintain the engine speed at 2500 rpm.
- Check that the needle on the voltmeter fluctuates 8 times or more in 10 seconds. If not, inspect the EFI system and replace the oxygen sensor, if necessary.
- With the engine at normal operating temperature, connect a voltmeter to the service connector located in the engine compartment. Using the service connector test wire lead (SST 09842-14010 or equivalent), connect the positive (+) probe to the red wire lead and the negative (-) probe to the black wire.
- Raise the engine speed to 2500 rpm for about 120 seconds.
- Maintain the engine speed at 2500 rpm and check that the needle of the voltmeter fluctuates 8 times or more in 10 seconds within 0-7 volts.
If this test is positive, the oxygen sensor is functioning properly. If not, inspect the other parts, hose connections and wiring of the air bleed system. If no problem is found, replace the oxygen sensor.Using an EFI Tester
- Install EFI tester SST 09991-00100 or equivalent to the EFI service connector and oxygen sensor check connector EFI.
- Start the engine and let it run until it reaches normal operating temperature. Connect a tachometer to the engine. On models with electronic ignition, attach the tachometer to the negative (-) side of the ignition coil, not to the distributor primary lead. Damage to the ignition control unit will result from improper connections.
- Race the engine at 2,500 rpm for approximately 90 seconds. Then maintain a steady engine speed at 2,500 rpm.
- Check that the oxygen sensor indicator light blinks 8 times or more in 10 seconds. If it does not, inspect the EFI system and replace the oxygen sensor if necessary.
- Stop the engine and remove all test equipment. Install the rubber caps to the EFI service connector and the oxygen sensor check connector.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Ensure that the engine and exhaust pipes are cold. Locate the oxygen sensor. Some sensors are on the front pipe, others are on the catalyst, you may have more than one.
- Spray a lubricant on the studs to ease removal.
- Disconnect the negative battery cable and disconnect the oxygen sensor wiring.
- Remove the oxygen sensor retaining nuts.
- Remove the oxygen sensor and gasket.
- Install the oxygen sensor with a new gasket.
- Apply a coating of anti-seize to the studs. Install the nuts and tighten to 14 ft. lbs. (20 Nm).
- Connect the oxygen sensor wiring.
- Connect the negative battery cable.