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

P2519

A/C Request A Circuit

General electrical fault on the A/C compressor request input A. This input tells the ECM that the HVAC controller wants the A/C compressor engaged. With the input invalid, the ECM cannot enable the compressor clutch — A/C does not cool, idle-up compensation is not applied.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 19

Possible causes

  • Open or shorted A/C request wire high
  • HVAC module not transmitting the request medium

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 80–500 €
  • Estimated time: 0.4–2 h
  • Component: ac request input a
  • Component: hvac module
  • 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