1998 Mitsubishi Montero CHECK ENGINE

Hi COMERCIALAUTOSERVICE,

Here is a description of the procedures. The sensor is located at rear of left bank catalytic converter.

DTC P0161: LEFT REAR HEATED OXYGEN SENSOR (HO2S) HEATER CIRCUIT MALFUNCTION

NOTE: This test applies to 3.0L vehicles equipped with California emissions only. For terminal identification, see TERMINAL IDENTIFICATION.

1. Disconnect left rear HO2S connector. Using DVOM, check resistance between HO2S terminals No. 1 and 3. Resistance should be 7-40 ohms. If resistance is not as specified, replace HO2S. Go to step 5). If resistance is as specified, go to next step.
2. Disconnect left rear HO2S connector. Turn ignition on. Using DVOM in Amps scale, connect a 20 ohm resistor between one DVOM lead and HO2S connector terminal No. 1. Connect other DVOM lead to ground. DVOM should read 0.5 amp or more. Turn ignition off. If DVOM reads as specified, go to next step. If DVOM does not read as specified, inspect connectors between left rear HO2S and MFI relay. Repair or replace connectors as necessary. Go to step 5). If connectors are okay, Repair wiring harness between left rear HO2S and MFI relay as necessary. Go to step 5).

3. Inspect wiring harness between left rear HO2S and PCM. Repair wiring harness as necessary. Go to step 5). If wiring harness is okay, go to next step.

4. Inspect left rear HO2S and PCM connectors for damage. Repair or replace connectors as necessary. Go to next step. If connectors are okay, replace PCM. Go to next step.

5. Road test vehicle and attempt to duplicate conditions that caused original complaint. Recheck for DTCs. If no DTCs are displayed, test is complete.