P0139

Tests 1 - 2:

Tests 3 - 7:

Test 8:

SYMPTOM
P0139 - 1/2 O2 SENSOR SLOW RESPONSE

WHEN MONITORED
With the engine running, engine at normal operating temperature, ambient air temperature greater than -7 °C (20 °F) and vehicle odometer is greater than 6437 Kilometers (4000 miles).

SET CONDITION
The Oxygen Sensor Signal voltage does not exceed 0.53 volts and does not fall below 0.35 volts once during the drive cycle.

POSSIBLE CAUSES
- Engine mechanical problem
- 1/2 O2 sensor ground circuit high resistance
- 1/2 O2 sensor ground circuit poor connection
- 1/2 O2 sensor signal circuit high resistance
- 1/2 O2 sensor signal circuit poor connection
- 1/2 O2 sensor slow response
- Exhaust leak
- 1/2 O2 sensor slow response does not reoccur