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

P24D7

EVAP System Pressure Sensor or Switch B Circuit Low

Same as P24D5 with the signal voltage below the plausible range. The evaporative system captures fuel vapor from the tank and purges it into intake; leaks or stuck purge valves leak hydrocarbons and cause emissions failures.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / D7

Possible causes

  • Signal shorted to ground high
  • Connector pins corroded - high contact resistance low
  • Harness chafing through insulation low

Symptoms

  • Check engine light on
  • Possible smell of fuel near tank or engine bay
  • Failed emissions inspection
  • Loose-cap warning may appear

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 80–280 €
  • Estimated time: 0.4–1.4 h
  • Component: evap pressure sensor b
  • MIL / check engine light
  • emissions-relevant

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