U0121 on Ford: How to Diagnose & Fix
Lost Communication with ABS Module
1 Ford model · 1 documented issue · 1 critical · $250-$3,200 repair
U0121 on Ford by model: symptoms, diagnosis and fix
NHTSA complaints include intermittent or sudden loss of power steering assist with warning messages, making the van difficult to steer at low speeds. Reports often describe the issue occurring after a restart, during parking maneuvers, or intermittently with electrical/communication faults. The Transit’s EPAS system can set steering-related DTCs and may require module diagnosis or replacement depending on root cause.
Common Symptoms
- Power steering assist reduced or lost
- Steering warning light/message
- Heavy steering at low speeds
- Intermittent return of assist after key cycle
- Steering-related communication faults
How to Fix
Scan for PSCM/ABS network faults, check battery/charging health and grounds, inspect steering rack electrical connections, and update software if applicable. If confirmed, replace the steering gear/EPAS rack or related control module per Ford diagnostics and perform steering angle/center calibration.
Sources for this issue (1)
U0121 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 U0121 mean on a Ford?
U0121 stands for "Lost Communication with ABS Module." U0121 is a network communication code meaning a control module on the vehicle's data bus has lost communication with the ABS (anti-lock brake system) module. Modern cars share information over a CAN bus, and when other modules stop receiving expected messages from the ABS unit, this code sets. Because the ABS module also handles traction control and stability control on most vehicles, you may see multiple warning lights and lost features. It points to a communication or power problem with the ABS module rather than a worn brake part. On Ford it is documented across 1 model: Transit.
What are the most common causes of U0121?
The most common causes of U0121 are: Loss of power or ground to the ABS module, Blown fuse feeding the ABS controller, Damaged, corroded, or loose ABS module connector, Open, shorted, or chafed CAN bus wiring, Internal failure of the ABS control module, Corrosion or water intrusion in connectors/harness, Faulty gateway module disrupting bus communication. The specific cause varies by vehicle.
How much does it cost to fix U0121 on a Ford?
Published repair estimates on Ford range from $250 to $3,200 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 U0121 on a different make?
View U0121 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.