1, 2 and 3 Digit Codes: 102

Scan Tool 102 (MIL 21):

Trouble Code Number
- Scan tool 102
- General scan tool P0133
- MIL 21

Fault Message
- Upstream HO2S Response

Background
- During closed-loop operation the PCM monitors the heated oxygen sensor response rate for proper operation.
- Response rate is the time required for the heated oxygen sensor to switch from lean-to-rich once the sensor is exposed to a richer than the idle air fuel mixture.
- If the response rate is below the acceptable limit, the PCM stores a diagnostic trouble code.

Range of Check
- Engine coolant temperature greater than 76°C (170°F)
- Approximately three minutes elapsed time after start-up.
- Vehicle has operated at more than 24mph (37km/h) for 75 seconds with engine coolant temperature at 76°C (170°F)
- Power steering pressure switch is off
- Vehicle is at idle with engine speed between 512 and 864 r/min.
- This test may be inhibited if the A/C is cycling too rapidly. (Testing with the A/C off is suggested)

Set Condition
- Heated oxygen sensor does not produce 0.67 volt output and/or does not perform enough switches within the test threshold time of 6 seconds.

Probable Cause
- Upstream heated oxygen sensor failed
- Exhaust system failed
- Pipes
- Manifold
- Seats
- Wiring harness and connectors failed
- PCM failed