Heated Oxygen Sensor Monitor

This monitor applies to DTCs P0133 and P0139. Following conditions must be met during the test:

• Engine coolant temperature must be 176°F (80°C) or more.
• Atmospheric temperature is 14°F (-10°C) or more.
• Selector lever is in "D" range A/T.

Monitor takes about 5 minutes to complete. This drive must be completed twice. To run monitor, use illustration. See Fig 1. Perform steps as follows:

1. Remove all test equipment from vehicle and install all components and connectors that were removed or disconnected during testing.
2. Start the engine.
3. Accelerate until the vehicle speed is 35-40 mph.
4. While keeping the accelerator pedal opening degree constant (M/T: 4th speed), keep the vehicle speed at 35-40 mph and travel for 120 seconds or more (during monitor).
5. Return vehicle to shop and turn ignition off.

Fig 1: Running Heated Oxygen Sensor Monitor

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.