Component Testing

SENSOR INSPECTION
1. Disconnect the oxygen sensor connector.
2. Check that there is continuity [approx. 12 Ohms at 20°C (68°F)] between oxygen sensor connector terminal (3) and terminal (4).
3. If there is no continuity, replace the oxygen sensor.
4. Warm up the engine until the engine coolant temperature exceeds 80°C (176°F).
5. Use jumper wires to connect oxygen sensor terminal (3) and terminal (4) to the battery (+) terminal and (-) terminal.

Caution: Be very careful when connecting the jumper wires because the oxygen sensor will be damaged if a mistake is made in the connecting terminals.

6. Connect a digital voltmeter between terminal (1) and terminal (2).
7. While repeatedly racing the engine, measure the output voltage of the oxygen sensor.


HEATER TEST
1. Disconnect the O2 sensor connector.
2. Using an ohm meter, check for continuity between O2 sensor connector terminals 3 and 4.
Voltage: Should exist

Osciloscope Test:

OSCILLOSCOPE TEST
1. Connect scope pickup probe to the sensor terminal 1.
2. Warm engine to operating temperature and keep it running at 2,000 RPM, check the waveform on the scope. If scope pattern is not as depicted in image, the sensor may be bad or there could be a fuel mixture problem. Refer to diagnosis by symptom for further system troubleshooting before replacing the assembly.


If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.

If the same trouble code reoccurs, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.