P1398

Tests 569 - 573:

Tests 574 - 575:

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
- Damaged crankshaft
- CKP sensor connector/wiring defective
- CKP sensor defective
- Improperly installed/loose sensor