U0121
Lost Communication with Anti-Lock Brake System (ABS) Control Module
What it means
The CAN messages from the ABS module are missing. ABS, ESP/ESC and traction control all become inactive (warning lamps illuminate), the speedometer may go to zero on cars that derive vehicle speed from the ABS module, and adaptive cruise control is disabled.
Is it safe to drive?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
ABS module unpowered (often a corroded ground or fuse)
highOne of the most commonly reported causes for this code — check this first.
CAN wiring to ABS broken
mediumA plausible cause — test and verify before replacing parts.
ABS module failed
mediumA plausible cause — test and verify before replacing parts.
Related help
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