U30xx codes: control modules and vehicle data
4 codes in this range, all generic — the same meaning on every make. Network codes about the control modules in general: an internal module fault, a module that didn’t shut down properly, a VIN that doesn’t match between modules, or battery voltage out of range.
What usually causes codes in this area
- Battery voltage problems
- A module that stays awake after the car is locked — and drains the battery
- A replacement module still carrying another car’s VIN
- An internal module fault
Can you keep driving?
Usually drivable; check the battery and have the modules scanned. If the battery keeps going flat, a module that won’t go to sleep may be the reason.
All U30xx codes
Read the codes from your own car
Plug an inexpensive Bluetooth LE or Wi-Fi OBD2 adapter into the port under the dashboard, and Brimly on your iPhone reads the stored, pending and permanent codes, explains each one offline and clears them once the fault is fixed. OBD diagnostics are part of Brimly Forever, a one-time purchase.
Requires iOS 18.1 or later. Free to download, with optional in-app purchases.