Lost Communication With ABS Control Module
What it means
Communication with the ABS (anti-lock brake) control module has been lost on the bus.
Symptoms
ABS, traction and stability warning lights; those systems may be disabled.
Common causes
Wiring/connector fault to the ABS module, power/ground loss, or a failed module.
Recommended action
Check the ABS module connector, wiring and power; brakes still work but ABS may not.
Related codes
FAQ — U0121
What does code U0121 mean?
Lost Communication With ABS Control Module. Communication with the ABS (anti-lock brake) control module has been lost on the bus.
What are the symptoms of U0121?
ABS, traction and stability warning lights; those systems may be disabled.
What causes U0121?
Wiring/connector fault to the ABS module, power/ground loss, or a failed module.
What should I do about U0121?
Check the ABS module connector, wiring and power; brakes still work but ABS may not.
General reference based on the SAE J2012 standard. Exact causes for your vehicle may differ — when in doubt, consult a workshop.
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