OBD2 · Network
U00xx codes: network wiring — CAN and communication buses
82 codes in this range, all generic — the same meaning on every make. The wires of the vehicle networks themselves — high-, medium- and low-speed CAN and other communication buses: open circuits, shorts to ground or to voltage, and shorts between the two bus wires.
What usually causes codes in this area
- Damaged or chafed network wiring
- Corroded connectors — water getting in is common
- A faulty module dragging the whole bus down
- Aftermarket accessories spliced into the wiring
Can you keep driving?
Get it checked promptly: a bus fault can take several systems offline at once, including ABS, the airbags or the engine itself.
All U00xx codes
| Code | Meaning |
|---|---|
| U0001 | High Speed CAN Communication Bus |
| U0002 | High Speed CAN Communication Bus Performance |
| U0003 | High Speed CAN Communication Bus (+) Open |
| U0004 | High Speed CAN Communication Bus (+) Low |
| U0005 | High Speed CAN Communication Bus (+) High |
| U0006 | High Speed CAN Communication Bus (-) Open |
| U0007 | High Speed CAN Communication Bus (-) Low |
| U0008 | High Speed CAN Communication Bus (-) High |
| U0009 | High Speed CAN Communication Bus (-) Shorted to Bus (+) |
| U0010 | Medium Speed CAN Communication Bus |
| U0011 | Medium Speed CAN Communication Bus Performance |
| U0012 | Medium Speed CAN Communication Bus (+) Open |
| U0013 | Medium Speed CAN Communication Bus (+) Low |
| U0014 | Medium Speed CAN Communication Bus (+) High |
| U0015 | Medium Speed CAN Communication Bus (-) Open |
| U0016 | Medium Speed CAN Communication Bus (-) Low |
| U0017 | Medium Speed CAN Communication Bus (-) High |
| U0018 | Medium Speed CAN Communication Bus (-) Shorted to Bus (+) |
| U0019 | Low Speed CAN Communication Bus |
| U0020 | Low Speed CAN Communication Bus Performance |
| U0021 | Low Speed CAN Communication Bus (+) Open |
| U0022 | Low Speed CAN Communication Bus (+) Low |
| U0023 | Low Speed CAN Communication Bus (+) High |
| U0024 | Low Speed CAN Communication Bus (-) Open |
| U0025 | Low Speed CAN Communication Bus (-) Low |
| U0026 | Low Speed CAN Communication Bus (-) High |
| U0027 | Low Speed CAN Communication Bus (-) Shorted to Bus (+) |
| U0028 | Vehicle Communication Bus A |
| U0029 | Vehicle Communication Bus A Performance |
| U0030 | Vehicle Communication Bus A (+) Open |
| U0031 | Vehicle Communication Bus A (+) Low |
| U0032 | Vehicle Communication Bus A (+) High |
| U0033 | Vehicle Communication Bus A (-) Open |
| U0034 | Vehicle Communication Bus A (-) Low |
| U0035 | Vehicle Communication Bus A (-) High |
| U0036 | Vehicle Communication Bus A (-) Shorted to Bus A (+) |
| U0037 | Vehicle Communication Bus B |
| U0038 | Vehicle Communication Bus B Performance |
| U0039 | Vehicle Communication Bus B (+) Open |
| U0040 | Vehicle Communication Bus B (+) Low |
| U0041 | Vehicle Communication Bus B (+) High |
| U0042 | Vehicle Communication Bus B (-) Open |
| U0043 | Vehicle Communication Bus B (-) Low |
| U0044 | Vehicle Communication Bus B (-) High |
| U0045 | Vehicle Communication Bus B (-) Shorted to Bus B (+) |
| U0046 | Vehicle Communication Bus C |
| U0047 | Vehicle Communication Bus C Performance |
| U0048 | Vehicle Communication Bus C (+) Open |
| U0049 | Vehicle Communication Bus C (+) Low |
| U0050 | Vehicle Communication Bus C (+) High |
| U0051 | Vehicle Communication Bus C (-) Open |
| U0052 | Vehicle Communication Bus C (-) Low |
| U0053 | Vehicle Communication Bus C (-) High |
| U0054 | Vehicle Communication Bus C (-) Shorted to Bus C (+) |
| U0055 | Vehicle Communication Bus D |
| U0056 | Vehicle Communication Bus D Performance |
| U0057 | Vehicle Communication Bus D (+) Open |
| U0058 | Vehicle Communication Bus D (+) Low |
| U0059 | Vehicle Communication Bus D (+) High |
| U0060 | Vehicle Communication Bus D (-) Open |
| U0061 | Vehicle Communication Bus D (-) Low |
| U0062 | Vehicle Communication Bus D (-) High |
| U0063 | Vehicle Communication Bus D (-) Shorted to Bus D (+) |
| U0064 | Vehicle Communication Bus E |
| U0065 | Vehicle Communication Bus E Performance |
| U0066 | Vehicle Communication Bus E (+) Open |
| U0067 | Vehicle Communication Bus E (+) Low |
| U0068 | Vehicle Communication Bus E (+) High |
| U0069 | Vehicle Communication Bus E (-) Open |
| U0070 | Vehicle Communication Bus E (-) Low |
| U0071 | Vehicle Communication Bus E (-) High |
| U0072 | Vehicle Communication Bus E (-) Shorted to Bus E (+) |
| U0073 | Control Module Communication Bus "A" Off |
| U0074 | Control Module Communication Bus "B" Off |
| U0075 | Control Module Communication Bus "C" Off |
| U0076 | Control Module Communication Bus "D" Off |
| U0077 | Control Module Communication Bus "E" Off |
| U0078 | Control Module Communication Bus "F" Off |
| U0079 | Control Module Communication Bus "G" Off |
| U0080 | Control Module Communication Bus "H" Off |
| U0081 | Control Module Communication Bus "I" Off |
| U0082 | Control Module Communication Bus "J" Off |
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.