P1391 — Intermittent Loss of CMP or CKP Signal
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P1391 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1391 means on specific makes
Dodge / Jeep / Ram / Chrysler CAUTION
The PCM saw an intermittent dropout of the camshaft or crankshaft position sensor signal. Causes intermittent stalling, hard starts, or no-starts that come and go. A very common Chrysler/Jeep driveability complaint.
- Failing cam (CMP) or crank (CKP) position sensor ($30-120)
- Wiring/connector chafe or corrosion ($20-150)
- Damaged tone/reluctor ring ($varies)
Check first: Wiggle-test the cam/crank sensor connectors; monitor RPM signal for dropouts while cranking/driving. CMP is a frequent failure.
Source: Allpar Chrysler list