Powertrain, generic (extended)

P24BA EVAP System Leak Detection Pump Pressure Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P24BA reports that the voltage from the leak check module's pressure sensor has fallen below the lowest value a working sensor can produce. In GM's ELCP tables (2018 Volt) the limit is 0.70 V, about 14 % of the reference or roughly 47 kPa absolute, with 640 failures in 800 samples taken every 12.5 ms; the check runs whenever the controller is awake and is Type B. Mitsubishi's 2023 Outlander PHEV sets P24BA when the signal stays under 0.1 V for 2 s. Subaru asks technicians to clear P24BA before chasing P2404 in the ELCM. A low signal mostly means a lost 5 V reference, a signal wire shorted to ground or a dead sensor. P24BB is the high-side counterpart; the leak test is suspended until the fault is gone.

Likely causes

Sensor signal wire shorted to ground
5 V reference open or pulled down by another sensor on the same supply
Pressure sensor inside the leak check module failed

Symptoms

  • Malfunction indicator lamp on
  • EVAP leak test not run

Repair estimate

DifficultyMediumDIY possible
Parts and labour€50–450
Time0.5–2 h

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

Parts involved

evap leak detection pump pressure sensor

Related codes

P24BBP24B9P24B8P24BCP2404

References: gsi.ext.gm.com, mitsubishitechinfo.com, static.nhtsa.gov.