Dodge P1398: Misfire Adaptive Numerator At Limit

Is your scanner showing Dodge P1398?
No worries. We'll show you what it means and how to deal with it.

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Dodge P1398: Misfire Adaptive Numerator At Limit

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What Does The Dodge P1398 Code Mean?

Engine started; ECT Sensor under 75ºF; engine runtime over 50 sec. ; A/C “OFF”; vehicle speed over 36 mph in 1st gear, or over 65 mph in high gear, followed by a closed throttle decel period. This code sets if the PCM detects one of the CKP Sensor target windows varies more than 2.86% from the reference window. Background – PCM needs to learn any variation in engine machining to detect when a misfire is present. CKP Sensor has 2 40 windows that are 180 apart. The window for Cylinders 1 and 4 is the reference window. It is checked against the window for Cylinders 2 and 3. The PCM checks for any variation to make engine speed adjustments.

What Are The Potential Causes Of The Dodge P1398 Code?

  • Base engine problem (i. e. , low cylinder compression)
  • CKP Sensor crankshaft target variation too large
  • CKP Sensor improperly installed or the CKP Sensor has failed
  • CKP Sensor signal circuit open or shorted (intermittent fault)
  • Tone wheel or pulse ring is damaged

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

Dodge P1398, DTCDECODE.

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