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

P2507

ECM/PCM Power Input Signal Low

The ECM/PCM switched-battery input reads below threshold while the ignition is on. Either the main relay does not close, the supply wire is broken or shorted to ground, or the battery is too low. Engine usually fails to start until the input recovers.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 07

Possible causes

  • Main relay does not pull in high
  • Open supply wire medium
  • Severely discharged battery medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 60–500 €
  • Estimated time: 0.4–2 h
  • Component: main relay
  • Component: power input wire
  • Component: battery
  • 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