P0135

Tests 198 - 203:

Test 204:

SYMPTOM
P0135 - 1/1 O2 SENSOR HEATER FAILURE

WHEN MONITORED
The O2 Heater Monitor runs during O2 sensor cool-down period, after a hot drive cycle, when engine is shut down with the ignition key turned "OFF".

SET CONDITION
Using O2 sensor signal voltage readings, during O2 sensor cool-down period, with heater OFF compared to O2 sensor signal voltage with heater ON.

POSSIBLE CAUSES
- Open ASD relay output circuit
- O2S heater control circuit open
- O2S heater control circuit shorted to ground
- Wiring harness intermittent defect
- O2S defective
- PCM defective