P1398 JEEP - Misfire Adaptive Numerator At Limit Condition

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What does this mean?

P1398 JEEP Possible Causes

  • Faulty Crankshaft Position (CKP) Sensor
  • Crankshaft Position (CKP) Sensor harness is open or shorted
  • Crankshaft Position (CKP) Sensor circuit poor electrical connection
  • Low cylinder compression

First diagnose P1398 JEEP code

    Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.

P1398 JEEP Tech Notes

There is a factory service bulletin for the following models:

1997 Wrangler
1996-1997 Cherokee
1996-1997 Grand Cherokee


A customer may experience a MIL (Check Engine Lamp) illumination due to an erroneous DTC P1398 - No Crank Sensor Learn. This DTC may also be displayed as a $BA - Adaptive Numerator at Limit. This condition may be caused by a momentary drop in the supply voltage to the powertrain control module.
This condition may occur when a normal, or higher, electrical load is applied to the battery. A momentary drop in the supply voltage to the PCM may be caused by a marginal battery or poor electrical connections from the battery to the PCM. The condition may be further aggravated by cold ambient temperatures or when the vehicle has been left unused for an extended period of time.

Cost of diagnosing the P1398 JEEP code

    Labor: 1.0

    The cost of diagnosing the P1398 JEEP code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

When is the P1398 JEEP code detected?

The Engine Control Module (ECM) has detected the actual crank sensor position does not agree with the expect crank sensor position.

P1398 JEEP Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1398 JEEP Meaning

With the engine running, the Powertrain Control Module (PCM) detects that the Actual Crankshaft Position (CKP) sensor signal level disagreed with the Expected CKP sensor signal level.
OBDII Code P1398 JEEP - Misfire Adaptive Numerator At Limit Condition - Engine-Codes.com

P1398 JEEP More Information

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