P1398moderate severityPowertrain
Misfire Adaptive Numerator At Limit
on 1999 Dodge Ram Van 5.9L V8 · 4WD
What this code means
The PCM misfire adaptive learning has reached its maximum correction limit. The system can no longer compensate for the detected misfire condition, indicating a persistent misfire problem that exceeds the adaptive range.
Symptoms
- Check Engine Light
- Noticeable engine misfire
- Rough idle
- Poor acceleration
- Failed emissions test
Common causes
- Worn spark plugs or ignition coils
- Fuel injector malfunction
- Low compression in one or more cylinders
- Vacuum leak at specific cylinder
- Crankshaft position sensor signal issue
Diagnostic steps
- Check for companion misfire codes (P0300-P0312) to identify affected cylinders
- Inspect spark plugs and ignition coils
- Perform fuel injector balance test
- Run compression test on suspected cylinders
- Check for vacuum leaks
Repair notes
Identify and repair the root cause misfire using companion codes; this code will clear once the misfire is resolved.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1