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

P2501

Generator Lamp/L-Terminal Circuit High

The L-terminal feedback from the alternator reads above the upper limit — short to supply or open ground side. Charging diagnostics cannot run cleanly.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 01

Possible causes

  • L-terminal shorted to supply high
  • Alternator regulator failed medium
  • Connector pins corroded - high contact resistance low

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–800 €
  • Estimated time: 0.5–3 h
  • Component: alternator
  • Component: charging warning lamp 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