P1398

Tests 1 - 2:

Tests 3 - 8:

SYMPTOM
P1398 - MISFIRE ADAPTIVE NUMERATOR AT LIMIT

WHEN MONITORED
Under closed throttle deceleration, A/C OFF, engine coolant temperature above 75 °F, longer than 50 seconds after engine start. Speed at which deceleration occurs must be sufficient for given gear range, eg, above 36 mph in 1st gear or above 65 mph in high gear.

SET CONDITION
When one of the CKP sensor target windows (40 degrees) has more than 2.86 % variance from the reference window.

POSSIBLE CAUSES
- Slots in flexplate defective
- CKP sensor defective
- CKP sensor not properly installed
- CKP sensor visibly defective
- Notches in crankshaft defective