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!

Powertrain generic / SAE

P0381

Glow Plug/Heater Indicator Circuit Malfunction

Electrical fault in the glow plug indicator lamp or relay circuit. The ECU monitors driver feedback to ensure the dashboard indicator can be commanded; an open or shorted circuit triggers this code.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number3 / 81

Possible causes

  • Indicator bulb or LED failed medium
  • Wiring or connector fault medium

Symptoms

  • Glow plug warning light on (often orange coil symbol)
  • Hard cold start or no start in cold weather
  • White smoke from exhaust during warm-up

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 20–200 €
  • Estimated time: 0.2–1.5 h
  • Component: glow plug indicator
  • Component: indicator wiring
  • 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