P1398

Test 1:

Tests 2 - 5:

Tests 6 - 7:

SYMPTOM
P1398-MISFIRE ADAPTIVE NUMERATOR AT LIMIT

WHEN MONITORED
Under closed throttle decel with A/C OFF, ECT above 75 °F, and more than 50 seconds after engine start.

SET CONDITION
One of the CKP sensor target windows has more than 2.86% variance from the reference window.

POSSIBLE CAUSES
- Intermittent condition
- CMP sensor connector/wiring
- CKP sensor connector/wiring
- Damaged tone wheel/flexplate (crankshaft)
- Crankshaft position sensor
- Faulty PCM