P0139

Tests 1 - 6:

SYMPTOM
P0139 - 1/2 O2 SENSOR SLOW RESPONSE

TEST NOTE
This symptom is diagnosed using the test P0133 - 1/1 O2 SENSOR SLOW RESPONSE.

WHEN MONITORED
Engine coolant temperature greater than 147 °F, vehicle speed greater than 10 mph, throttle OFF idle for 2 minutes. Bring vehicle to a stop and allow to idle transmission in DRIVE (auto) or in NEUTRAL (manual).

SET CONDITION
The oxygen sensor signal voltage is switching from below 0.27 volts to above 0.62 volts and back fewer times than required.

POSSIBLE CAUSES
- Exhaust leak
- O2S sensor ground circuit voltage drop
- O2S signal circuit voltage drop
- Wiring harness intermittent problem
- O2S