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

U0307

Software Incompatibility with Glow Plug Control Module

The glow plug controller and the engine ECU run incompatible software versions. Cold-start preheating may be inhibited and the glow plug warning lamp can stay on.

SystemNetwork
Typegeneric / SAE
GroupU0
Range / number3 / 07

Possible causes

  • Software flash mismatch after parts swap 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: hard
  • DIY: shop recommended
  • Estimated cost: 80–500 €
  • Estimated time: 0.5–2 h
  • Component: glow plug module
  • Component: ecm
  • 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