P0320 on Jeep: How to Diagnose & Fix
Ignition/Distributor Engine Speed Input Circuit Malfunction
4 Jeep models · 4 documented issues · 4 critical · $30-$600 repair
P0320 on Jeep by model: symptoms, diagnosis and fix
The crankshaft position sensor (CKP) on the 4.7L (and 4.0L) Grand Cherokee commonly fails from heat-soak: it works when cold but its internal resistance rises when hot, so the PCM loses the crank signal and the engine won't restart until it cools 30-60 minutes, or it stalls randomly while driving. A cranks-but-no-start after a hot soak is the classic signature and a top WJ search.
Common Symptoms
- Cranks but will not start when hot; restarts after cooling down
- Random stalling while driving with immediate/eventual restart
- Intermittent no-crank-signal
- Tachometer drops to zero while stalling
How to Fix
Verify with a scan tool (loss of CKP signal / no RPM during crank) rather than parts-swapping. Replace with a quality sensor — Mopar crankshaft position sensor 56028666AB fits 1999-2004 4.7L (56028133-series is the CAMSHAFT sensor, do not confuse). Use OEM Mopar or premium NGK/NTK; cheap sensors frequently fail again. On some 4.7L applications the starter must be removed for access.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar crankshaft-position sensorOEMMopar 56028666AB
Replacement after testing confirms the CKP sensor itself failed on a 1999-2004 Grand Cherokee 4.7L Fitment/availability: 56028666AB is the exact reviewed genuine sensor and supersedes 56028666AA, 56028136AC/AD and 56028137AC. Confirm VIN…
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Owner tips & cautions
- WarningDo not replace the sensor from P0320 alone. The factory tree also lists CKP supply, ground, signal wiring, cam signal, and PCM causes.
- WarningRecall 04V-112 is a limited 2004 4.0L campaign; it does not make a 1999-2004 4.7L sensor replacement a recall repair.
- TipThe 4.7L sensor sits above the starter. Follow the factory O-ring, flush-seating, and torque precautions so the new sensor is not damaged during installation.
Sources for this issue (3)
The crankshaft position sensor on the 4.0L I6 and 2.5L I4 XJ is a classic thermal-failure item. Internal components and wiring degrade with age and heat, so the sensor works cold but drops signal once the engine reaches operating temperature. Without a CPS signal the PCM cuts spark and fuel, producing a stall or a crank-but-no-start that mysteriously 'fixes itself' after the engine cools. It is one of the most frequently discussed XJ failures in enthusiast communities and typically strikes around 125,000-175,000 miles.
Common Symptoms
- Crank but no start
- Engine stalls when hot then restarts after cooling
- Intermittent sudden stalling while driving
- No tachometer signal while cranking
How to Fix
Replace the crankshaft position sensor (mounted at the bell housing / transmission). The 4.0L PCM is notoriously picky about signal quality, so owners strongly recommend a Mopar (OEM) or NTK sensor rather than a cheap generic unit, which frequently causes repeat failures. It is a roughly one-hour job; a scan tool showing loss of RPM signal while cranking helps confirm before replacing.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Crown 56027866AC crankshaft-position sensor for the 1997-1999 4.0L branchOEM56027866AC (supersedes 56027866AB)
Test-confirmed crankshaft-position signal failure on a 1997-1999 Cherokee XJ 4.0L Fitment/availability: 56027866AC is explicitly limited to 1997-1999 XJ Cherokee 4.0L. Confirm VIN, connector and transmission calibration; it is not the 2.…
- Crown 56027865AB crankshaft-position sensor for the 1997-1999 2.5L branchOEM56027865AB
Test-confirmed crankshaft-position signal failure on a compatible 1997-1999 Cherokee XJ 2.5L Fitment/availability: 56027865AB is the Mopar-listed 1997-2001 XJ 2.5L crank sensor and the product page is engine-specific. Confirm model year,…
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Sources for this issue (3)
The crankshaft position sensor (CPS) on the 4.0L (and 2.5L) inline engines mounts on the transmission bellhousing and is exposed to severe heat soak. As it ages it develops intermittent thermal failure: the engine stalls without warning once hot, then refuses to restart until it cools, after which it runs fine again — a maddening, hard-to-replicate fault. Frequently the CPS fails with NO check-engine light and NO stored code, so it is commonly misdiagnosed. It is a top-searched TJ/early-Wrangler stalling complaint and a roadside-safety concern because the stall is sudden.
Common Symptoms
- Engine stalls suddenly while driving, especially when hot
- Will not restart until the engine cools, then runs normally
- Cranks but no start when hot
- Often no check-engine light and no stored DTC
- Intermittent stumble/backfire
- Hard starting in rainy/humid weather
How to Fix
When the engine stalls hot and won't restart, unplugging and reconnecting the CPS connector (near the back of the intake) often resets the PCM and the engine fires — a strong indicator the CPS is failing. Replace the crankshaft position sensor with a Mopar or NTK/NGK unit (Mopar 56027866AE for many 4.0L applications; 4727451AA covers 2003-2011 TJ/JK 3.8L & 4.0L). Avoid bargain aftermarket sensors — out-of-tolerance units cause repeat no-starts. No relearn required; verify with a hot road test.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Crown 56027865AB crankshaft-position sensorOEMCrown 56027865AB
Manual-transmission/early-engine sensor replacement after hot testing confirms signal dropout Fitment/availability: 1997-2004 Wrangler TJ 4.0L manual-transmission branch; the underlying application family also covers specified 1997-2002 …
- Crown 4897321AA crankshaft-position sensorOEMCrown 4897321AA
Early automatic-transmission sensor replacement after hot testing confirms signal dropout Fitment/availability: 1997-2002 Wrangler TJ 4.0L automatic-transmission branch. Confirm connector and transmission; not the manual or 2003-2006 bra…
- Standard Motor Products PC243 crankshaft-position sensorOEMStandard PC243 / Mopar cross 4727451AA
Later TJ 4.0L sensor replacement after hot testing confirms crank-signal dropout Fitment/availability: Crosses Mopar 4727451AA for specified 2003-2006 Wrangler TJ 4.0L applications; verify transmission/connector and exact catalog fit bef…
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Sources for this issue (2)
Libertys of both generations lose the crank reference signal to the PCM, setting P0320 and shutting the engine off without warning - owners describe the vehicle simply dying at speed, sometimes restarting immediately and sometimes not for hours, and often producing a limp-mode condition. The fault is heat-sensitive, so it typically appears after the engine is warmed and is hard to reproduce cold at a shop. The forum record contains a real diagnostic warning: on Chrysler powertrains, crank and cam sensor codes are misleading, and the failure is frequently in the connector or the harness (oil-contaminated pins, chafed wiring) or in the PCM rather than in the sensor itself - multiple owners report P0320 returning immediately after a new sensor. Stalling in traffic makes this a safety issue, not just a driveability complaint.
Common Symptoms
- Engine stalls without warning while driving
- Intermittent crank but no start, often when hot
- Rough idle and hesitation
- Check engine light for no crank reference signal
- Vehicle enters limp mode
- Restarts normally after cooling down
How to Fix
Scan and record all codes - P0320 arriving with P1391 or P0340 changes the diagnosis. Before replacing the sensor, inspect the crank sensor connector and pigtail for oil intrusion, spread or corroded terminals, and chafe where the harness passes near the bellhousing; clean and repair as needed. Then replace the crankshaft position sensor with a Mopar or equivalent-quality unit - cheap aftermarket crank sensors are a documented repeat-failure source on these vehicles. If the code returns with a known-good sensor and a sound harness, the PCM is the remaining suspect. No recall covers this.
Sources for this issue (3)
P0320 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0320 mean on a Jeep?
P0320 stands for "Ignition/Distributor Engine Speed Input Circuit Malfunction." The ECM/PCM detected a malfunction in the ignition or distributor engine-speed (RPM) input circuit. This circuit supplies the engine-speed reference used for spark timing and fuel control; a general fault here (open, short, or signal loss) is flagged as P0320. On distributorless systems this maps to the crank/ignition RPM reference. On Jeep it is documented across 4 models: Grand Cherokee, Cherokee, Wrangler, Liberty.
What are the most common causes of P0320?
The most common causes of P0320 are: Faulty crankshaft/distributor RPM pickup sensor, Damaged wiring or connector in the RPM input circuit, Poor ground or corroded connector, Faulty ignition module, Air gap or damaged reluctor/trigger wheel. The specific cause varies by vehicle.
How much does it cost to fix P0320 on a Jeep?
Published repair estimates on Jeep range from $30 to $600 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0320 on a different make?
View P0320 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.