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

P0231

Fuel Pump Secondary Circuit Low

The voltage on the secondary side of the fuel pump circuit is below the expected level when the pump is commanded on. Often caused by a failed pump motor, corroded ground, or wiring fault.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number2 / 31

Possible causes

  • Fuel pump motor failed or worn high
  • Pump ground point corroded medium
  • Connector pins corroded - high contact resistance low

Symptoms

  • Check engine light on
  • Hard start, no start, or stalling under load
  • Power loss especially at high load or rpm
  • Possible long cranking time

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 150–800 €
  • Estimated time: 1–4 h
  • Component: fuel pump
  • Component: fuel pump 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