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

U0002

High Speed CAN Communication Bus Performance

The high-speed CAN bus is functional but performance is degraded — frame errors, bit errors or excessive bus load have been detected. Communication may be intermittent rather than completely lost, leading to sporadic warning lamps.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number– / 02

Possible causes

  • Corrosion or poor contact in CAN connectors high
  • Electromagnetic interference (aftermarket electronics) medium
  • One module sending malformed frames 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: 80–1200 €
  • Estimated time: 1–6 h
  • Component: can bus wiring
  • Component: control module
  • MIL / check engine light

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