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

P2635

Fuel Pump A Low Flow / Performance

The ECU detects insufficient fuel flow from fuel pump A. Either the pump is worn out, the supply line is restricted, or the pressure regulator does not allow proper flow.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number6 / 35

Possible causes

  • Worn fuel pump high
  • Clogged fuel filter medium
  • Pressure regulator fault 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: 150–700 €
  • Estimated time: 0.5–2.5 h
  • Component: fuel pump
  • Component: fuel filter
  • Component: fuel pressure regulator
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

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