C2120 on Jeep: How to Diagnose & Fix
Manufacturer-Specific TPMS Transmitter/Sensor Fault
1 Jeep model · 1 documented issue · $300-$1,500 repair
C2120 on Jeep by model: symptoms, diagnosis and fix
The electronic locking rear differential (standard on Rubicon and Mojave) can fail to engage or disengage. The most commonly reported cause is the locker position sensor inside the axle: it sits over a magnet that collects metallic wear debris from the gear oil, and gear oil can seep into the sensor and short it, so the locker never confirms engagement. Worn locking components inside the carrier are a less common cause. When stuck in the locked position, the differential causes binding and tire chirping on pavement. When stuck disengaged, it fails to provide traction when needed.
Common Symptoms
- E-locker will not engage when switch is pressed
- Locker indicator light flashes but does not go solid
- Differential stays locked on pavement causing tire chirp
- Grinding noise when attempting to engage locker
- Axle locker warning light on dashboard
- Clicking from rear differential area
How to Fix
Diagnose with scan tool to confirm a locker circuit or position sensor fault, and verify the locker is being commanded correctly (4-Low, within speed limits). At the next gear oil change, remove the locker position sensor (one Torx screw), clean the metallic debris off the magnet, and replace the sensor if gear oil has entered it (it looks two-toned). If the locking ring inside the differential is damaged, the differential carrier requires replacement. After repair, perform an e-locker cycle test (engage/disengage 5 times) to confirm proper operation.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar axle-locker actuator kit, current AB revisionOEMMopar 68391561AB (supersedes 68391561AA)
A scan/current/travel-confirmed failed factory axle-locker actuator on a compatible Gladiator axle Fitment/availability: 68391561AB is the current actuator and supersedes 68391561AA plus earlier numbers. Confirm VIN, front/rear axle, axl…
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Sources for this issue (1)
C2120 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 C2120 mean on a Jeep?
C2120 stands for "Manufacturer-Specific TPMS Transmitter/Sensor Fault." C2120 is a manufacturer-specific chassis code within the Tire Pressure Monitoring System family (frequently Toyota/Lexus). It generally indicates a fault with a tire pressure transmitter (wheel sensor) or its signal reception, such as a missing, weak, or implausible transmission. The exact definition varies by maker. The TPMS warning light typically illuminates and one or more tire pressures may be unavailable; verify pressures manually. On Jeep it is documented across 1 model: Gladiator.
What are the most common causes of C2120?
The most common causes of C2120 are: Weak or dead TPMS sensor battery, Faulty or missing tire pressure sensor, Sensor ID not registered/initialized, Receiver, antenna, or wiring fault, Radio-frequency interference, TPMS control module fault. The specific cause varies by vehicle.
How much does it cost to fix C2120 on a Jeep?
Published repair estimates on Jeep range from $300 to $1,500 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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.