The P1390 code on your 2023 Jeep Grand Cherokee indicates intermittent loss of either the camshaft position (CMP) or crankshaft position (CKP) sensor signals. This Stellantis-specific code affects your Grand Cherokee's 3.6L Pentastar V6, 5.7L HEMI V8, or 2.0L turbocharged 4-cylinder engine's timing and synchronization systems.
Understanding P1390 on Grand Cherokee
Both CMP and CKP sensors must work together to provide the PCM with precise engine position information. Code P1390 sets when the PCM detects intermittent signal loss from either sensor, causing momentary loss of engine position reference. This can cause misfires, rough running, or stalling during the signal dropout.
Common Symptoms
- Check engine light on
- Intermittent engine stumble or misfire
- Random stalling
- Rough running that comes and goes
- Hard starting (hot or cold)
- Engine hesitation during acceleration
- May run fine most of the time with occasional issues
Primary Causes
- Failing CMP or CKP sensor
- Loose or damaged sensor connector
- Wiring harness intermittent open or short
- Sensor air gap too large
- Oil contamination affecting sensor
- Heat-related wiring breakdown
- Damaged reluctor ring or tone wheel
- PCM connector issue
Diagnostic Procedure for 2023 Grand Cherokee
P1390 indicates intermittent issues, which are harder to diagnose than complete failures. Monitor both CMP and CKP signals with a scan tool during test drive - look for signal dropouts. Wiggle test sensor connectors and wiring while monitoring signals. Inspect both sensors for oil contamination or physical damage. Check for TSBs as certain model years have known sensor issues. Test sensor resistance when cold and hot to identify heat-related failures.
Repair Solutions
Replace the suspect sensor - if P1390 is accompanied by CMP or CKP specific codes, start with that sensor. Repair any loose or damaged connectors. Address wiring issues with proper repairs, especially in areas exposed to heat. Clean oil contamination from sensors. If reluctor rings show damage, repair accordingly. After repairs, extended test drive to verify intermittent condition is resolved.