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

P26A1

Exhaust Aftertreatment Glow Plug Circuit Low

The aftertreatment glow plug current is below expected. Either the element is partially open or supply is undersized.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number6 / A1

Possible causes

  • Partial element failure raises resistance high
  • Supply voltage drops under load medium
  • Connector pins corroded - high contact resistance 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: shop recommended
  • Estimated cost: 120–700 €
  • Estimated time: 0.8–3 h
  • Component: aftertreatment glow plug
  • Component: supply circuit
  • 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