U0121 on Honda
Lost Communication with ABS Module
U0121 on Honda vehicles indicates lost communication with abs module. Au7o has documented this code across 1 Honda model — most commonly on HR-V. 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. Typical repair costs on Honda range from $150 to $2,000, depending on the specific model and root cause.
Common Causes of U0121
- •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
U0121 on Honda by Model
Honda HR-V(1 issue)
- Electrical System Issues and Battery Drain2016-2023
Honda HR-V models across all years experience electrical system problems including parasitic battery drain, premature battery failure, and stability control module failures. Owners report dead batteries after 24-48 hours of sitting, with the vehicle not holding a charge. Common causes include faulty door lock actuators causing constant drain, infotainment system staying on, and failing stability control modules. Stability control module replacement can cost $1,500+.
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View U0121 across all makes →Frequently Asked Questions
What does U0121 mean on Honda?▼
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 Honda specifically, this code is documented across 1 model.
What causes U0121 on Honda vehicles?▼
Common causes on Honda: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix U0121 on a Honda?▼
Repair costs on Honda range from $150 to $2,000, depending on the specific model and root cause.
Which Honda models have U0121 documented?▼
Au7o has documented U0121 on 1 Honda model: HR-V.