U0121
Lost Communication With Anti-Lock Brake System (ABS) Control Module A
Network · Generic (all makes)System: Network/Communication + ABS/Stability Control
Safe to drive short term. Book a repair.
Likely causes
- ABS module not responding
- Corroded ABS module connector
- Low voltage
What to check first
ABS and stability control are likely off. Check the ABS fuses and connector, then the module.
Typical repair cost
$100 – $1,500
Independent-shop parts and labor for the usual fix. Your price depends on the actual cause and the vehicle.
Next step
General information, not a diagnosis of your vehicle. Repair costs are typical shop ranges, not quotes.