OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Network generic / SAE

U0001

High Speed CAN Communication Bus

A general fault on the high-speed CAN bus has been detected. This bus typically connects powertrain modules (ECM, TCM, ABS) at 500 kbit/s and a fault disables communication between them, often triggering multiple secondary DTCs in other modules.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number– / 01

Possible causes

  • CAN-High and CAN-Low shorted together high
  • Open circuit in CAN bus wiring high
  • Terminating resistor failed (not 60 ohms across bus) medium

Symptoms

  • Multiple warning lights may illuminate
  • Affected modules may go into limp mode or shut down
  • Specific functions inoperative depending on module
  • Diagnostic tools may show communication faults

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 80–1500 €
  • Estimated time: 1–8 h
  • Component: can bus wiring
  • Component: can terminating resistor
  • Component: control module
  • MIL / check engine light
  • limp mode possible

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication