Powertrain, generic (extended)

P24D6 EVAP System Pressure Sensor/Switch B Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24D6 is a plausibility fault of EVAP pressure sensor B. GM's 2023 table 23OBDG03A checks the canister vapour pressure sensor at the start of a cold drive: after more than 3,600 s soak the offset must sit within a window around barometric pressure; a filtered ratio above 0.73 sets the code, Type A. GM bulletins 24-NA-162 and 24-NA-258 trace P24D6 on 2024–2025 Silverado and Sierra HD 6.6L trucks to a narrow-range sensor fitted at the plant (about 1.5 V instead of 2.625 V at rest). Mitsubishi's 2023 Outlander PHEV compares tank, differential and canister pressures for 180 s during the engine-off test. Audi lists it for V6/V8 sensor G950, FCA for 2017–2018 Giulia software. P24D7/P24D8 are hard voltage limits.

Likely causes

Wrong sensor version installed (GM HD trucks, narrow-range instead of wide-range)
Sensor offset drifted away from barometric pressure
Kinked hose or blocked port at the sensor
Engine control software needing an update (FCA, Audi)

Symptoms

  • Malfunction indicator lamp on
  • Other EVAP codes such as a switching valve fault may appear alongside
  • No driveability change

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–400
Time0.5–2 h

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

Parts involved

evap pressure sensor b

Related codes

P24D5P24D7P24D8P24D9P0451P2B7B

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