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

U0300

Internal Control Module Software Incompatibility

A control module has detected that its software version is incompatible with another module on the bus. Most often after a partial update, mismatched coding, or fitting a used module from a different vehicle.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number3 / 00

Possible causes

  • Software/calibration mismatch between modules high
  • Used module from different vehicle fitted medium
  • Incomplete or interrupted module flash 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: 80–800 €
  • Estimated time: 0.5–3 h
  • 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