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

U0168

Lost Communication with Vehicle Immobilizer Control Module

The ECU cannot reach the immobilizer / vehicle security module. Engine start is usually blocked because the rolling code cannot be exchanged.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number1 / 68

Possible causes

  • Immobilizer module unpowered high
  • Wiring or antenna ring damaged medium
  • Gateway module routing CAN messages incorrectly 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: hard
  • DIY: shop recommended
  • Estimated cost: 80–900 €
  • Estimated time: 0.5–4 h
  • Component: immobilizer module
  • Component: can bus wiring
  • 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