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

P0683

Glow Plug Control Module 1 to PCM Communication Circuit

A circuit fault is detected on the communication line between glow plug control module 1 and the PCM. The PCM cannot read plug status and cannot command preheat.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number6 / 83

Possible causes

  • Open or short on communication wire high
  • Gateway module routing CAN messages incorrectly low
  • CAN terminating resistor (120 Ω) drifted out of spec low

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: medium
  • DIY: possible
  • Estimated cost: 80–400 €
  • Estimated time: 0.5–2 h
  • Component: glow plug control module 1
  • Component: gpcm communication wire
  • MIL / check engine light
  • emissions-relevant

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