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 or reserved

U3008

Control Module Ground A

The control module detects a problem on its ground reference A — open ground, high resistance to chassis, or floating ground potential.

SystemNetwork
Typegeneric or reserved
GroupU3
Range / number– / 08

Possible causes

  • Ground stud corroded high
  • Ground connection loose 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: easy
  • DIY: possible
  • Estimated cost: 10–200 €
  • Estimated time: 0.3–1.5 h
  • Component: module ground a
  • Component: ground strap
  • 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