Powertrain, generic (extended)

P2DDB EVAP System Leak Detection Pump Stuck On

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2DDB reports a leak detection pump that keeps running, or keeps moving air, after the engine computer has turned it off. GM names P2DDB in its 2025 summary tables only as a blocking code for the ELCP leak test, while its own stuck-on check runs as P145D: with the pump commanded off, the switching valve is moved from vent to pump position halfway through the test, and a pressure shift above 1,000 Pa within 8 s, or more than 1,180 Pa of vacuum after 14 s in a later step, shows the pump is still pulling; Type B over two trips. Mitsubishi files a pump stuck on together with stuck off as P24C0. Because a running pump distorts every reference reading, the leak result becomes useless. Hard circuit faults point to P2401 or P2402 first; stuck off is P2DDA.

Likely causes

Internal fault of the leak check module (pump or its electronics)
Pump supply permanently live, e.g. stuck relay or shorted output stage
Control wire chafed against a powered line

Symptoms

  • Check engine light on
  • Humming from the tank area after the car is switched off
  • Leak test results unusable, EVAP readiness incomplete

Repair estimate

DifficultyMediumDIY possible
Parts and labour€100–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

evap leak detection pumpwiring harnessecm

Related codes

P2DDAP2DD9P2401P2402P24C0P24B9

References: gsi.ext.gm.com, mitsubishitechinfo.com, law.cornell.edu.