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P1391

Intermittent Loss of CMP Or CKP.

  • Dodge
  • Powertrain
  • Manufacturer code
  • High severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
3
AreaIgnition system or misfire
91
FaultThe specific fault in that area

What it means

On Dodge, P1391 means the powertrain control module has detected an intermittent loss of the camshaft position (CMP) or crankshaft position (CKP) sensor signal. The module saw the signal drop out or become implausible while the engine was cranking or running, then return. Because the fault comes and goes, it often points to a wiring, connector or sensor problem rather than a permanent failure.

Symptoms

  • Engine stalls or cuts out unexpectedly, sometimes restarting straight away
  • Long cranking or intermittent no-start
  • Misfire, hesitation or surging while driving
  • Rev counter dropping or flickering
  • Engine warning light on, sometimes only intermittently
  • Rough running that comes and goes with heat or vibration

Possible causes

  • Damaged, chafed or corroded wiring to the CKP or CMP sensorlikely
  • Loose, corroded or contaminated sensor connector terminalslikely
  • Failing crankshaft or camshaft position sensor, often heat-relatedlikely
  • Poor sensor mounting, incorrect air gap or oil contamination on the sensorpossible
  • Damaged or loose reluctor/tone wheel or trigger wheelpossible
  • Poor power or ground supply to the sensors or powertrain control modulepossible
  • Fault inside the powertrain control modulerare

How to diagnose

  1. Read all stored and pending codes and note any related CMP, CKP or misfire codes, then check freeze frame data for engine speed, temperature and load when the fault set
  2. Check for technical service information or known issues for the specific model and engine, as sensor locations and layouts vary
  3. Visually inspect the CKP and CMP sensors, their wiring and connectors for chafing, heat damage, oil contamination, corrosion or loose pins
  4. With the engine running, gently wiggle the harness and connectors while watching live engine speed data for dropouts
  5. Check sensor mounting, fixings and condition of the sensor tip, and look for metal debris or damage
  6. Check the sensor supply voltage, ground and signal against the manufacturer's specification
  7. Inspect the reluctor or tone wheel for damage, looseness or missing teeth where accessible
  8. Scope the CKP and CMP signals together to check for dropouts and correct timing relationship

How to fix

  • Repair or replace damaged wiring and restore proper connections
  • Clean or replace corroded connectors and terminals
  • Replace the faulty crankshaft or camshaft position sensor, and secure it correctly
  • Replace or correctly secure a damaged or loose reluctor or tone wheel
  • Repair power or ground supply faults to the sensors or control module
  • Replace or have the powertrain control module checked only after all wiring and sensor faults are ruled out

Can I keep driving?

High severity

Avoid driving until it is checked, as the engine may stall without warning, which can cause loss of power assistance and be unsafe in traffic. If it must be moved, keep the journey very short.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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