P24B9EVAP System Leak Detection Pump Pressure Sensor Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P24B9 means the leak check module's pressure sensor delivers a signal that is electrically valid but not believable. GM's 2018 Volt table (ELCP) compares the absolute sensor reading with barometric pressure from the MAP sensor while pump and valve rest; a gap above 3,000 Pa at the engine-off wake-ups (roughly 4 to 11 h after shutdown) or above 15,000 to 20,000 Pa while driving counts as a fail, 50 of 63 samples, Type B. Mitsubishi's 2023 Outlander PHEV instead counts signal noise during the key-off test and fails after more than 20 fluctuations. FCA fixed P24B9 with PCM software on the 2017 Pacifica and the 2025 Grand Cherokee 4xe (18-079-25). P24BA and P24BB are the hard voltage limits.
- What you may notice
- Malfunction indicator lamp on
- EVAP leak test aborted, readiness not set
- Usually no noticeable change in driving
- Likely causes
- LikelyPressure sensor in the leak check module drifted or noisy
- PossibleEngine control software needing an update (FCA bulletins)
- PossibleMoisture or dirt in the module's pressure port
- RareChafed wiring or loose pin causing signal disturbance
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.