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

P2505

ECM/PCM Power Input Signal

The ECM/PCM monitors the main switched battery feed (typically terminal 15 / ignition-switched supply via the main relay). A general fault is reported — either the input is missing entirely or it does not match the expected timing relative to ignition state. Engine may not start or stay running.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 05

Possible causes

  • Failed main relay high
  • Blown fuse on the ECM power feed medium
  • Corroded connector pin at the ECM medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 60–600 €
  • Estimated time: 0.5–2.5 h
  • Component: main relay
  • Component: power input wire
  • 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