Test O2S (1.8L) - Oxygen Sensor

NOTE: Enter this test only when Code 15 (lean) or Code 17 (rich) is displayed during self-test procedures (KOEO or KOER). This test is intended to diagnose O2S circuit.

NOTE: Voltage that remains more than .55 volt indicates a continuously rich condition. Voltage that remains less than .55 volt indicates a continuously lean condition. Rich or lean conditions may also be an indication of another problem.

1) Check O2S Voltage Ensure engine is at normal operating temperature. Turn ignition off. Disconnect O2S connector. Measure voltage at O2S connector. Voltage should increase as engine speed increases and decrease as engine speed decreases; voltage should be 0.2-0.8 volt at idle. If voltage is as specified, go to next step. If voltage is not as specified, replace O2S.

2) Check O2S Circuit Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between O2S test pin at breakout box and O2S connector. If resistance is less than 5 ohms, O2S circuit is okay. If no other problem or code is found, replace PCM.