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

U0325

Software Incompatibility with Auxiliary Heater Control Module

The auxiliary heater module is running incompatible software. The pre-heater may not start or aborts operation early.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number3 / 25

Possible causes

  • Incompatible flash version high
  • Gateway module routing CAN messages incorrectly low
  • CAN terminating resistor (120 Ω) drifted out of spec low

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: medium
  • DIY: shop recommended
  • Estimated cost: 60–400 €
  • Estimated time: 0.3–1.5 h
  • Component: auxiliary heater

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