P1398

Tests 1 - 2:

Tests 3 - 8:

SYMPTOM
P1398 - MISFIRE ADAPTIVE NUMERATOR AT LIMIT

WHEN MONITORED
Under closed throttle DECEL, A/C OFF, engine coolant temperature > 23 °C (75 °F), longer than 50 seconds after engine start. The speed at which the deceleration occurs must be sufficient for the given gear range, e.g., > 36 km/h (36 mph) in first gear or > 104 km/h ( > 65 mph) in high gear.

SET CONDITION
When one of the CKP Sensor target windows 15 °C (60 °F) has more than 2.86% variance from the reference window.

POSSIBLE CAUSES
- CKP sensor connector observable defect
- CKP sensor defective
- CKP sensor not properly installed
- Notches in crankshaft defective
- Slots in flexplate defective