Engine Management

Scan Tool 32 (MIL 21):

Trouble Code Number
- Scan tool 32
- General Scan Tool P0134
- MIL 21

Fault Message
- Upstream HO2S Stays at Center

Background
- Sensor output voltage is checked.
- If voltage stays at center instead of switching, an open circuit is likely.

Range of Check
- 2 minutes after starting engine
- Engine coolant temperature: More than 80°C (176°F)

Set Condition
- Neither rich nor lean condition is detected from the front bank heated oxygen sensor input. (voltage is 0.5 volts for 1.5 minutes)

Probable Cause
- Heated oxygen sensor -- front -- failed
- Sensor signal circuit open
- PCM failed