P24BB code meaning
EVAP System Leak Detection Pump Pressure Sensor Circuit High
Powertrain system Generic code P24xx codes Check engine light
What P24BB means
P24BB is stored when the leak check module's pressure signal climbs above the top of its usable range. GM uses 4.85 V, about 97 % of the reference or roughly 120 kPa, again with 640 of 800 samples and Type B; the limit appears unchanged from the 2018 Volt up to GM's 2025 table 25OBDG03A for conventional ELCP systems. Mitsubishi's 2023 Outlander PHEV flags the code above 4.9 V lasting 2 s. Subaru lists P24BB with P24BA and P24B9 as faults to clear first when P2404 appears. A reading pinned high usually comes from an open ground, a signal wire touching a voltage source or an internal sensor fault, rarely from real pressure. P24BA covers the low side; P24B9 a signal that stays in range but disagrees with barometric pressure.
P24BB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P24BB
- Malfunction indicator lamp on
- EVAP leak test not run, readiness incomplete
Common causes of P24BB
- Most likelyOpen sensor ground or signal wire, letting the input float high
- PossibleSignal wire shorted to the 5 V reference or battery voltage
- PossiblePressure sensor inside the leak check module failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP leak detection pump pressure sensor
What each part of P24BB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| BB | The exact fault in that area. |
What to do next
- Note P24BB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P24BB
What does P24BB mean?
P24BB means "EVAP System Leak Detection Pump Pressure Sensor Circuit High". P24BB is stored when the leak check module's pressure signal climbs above the top of its usable range. It is a generic code, so it means the same on every make.
Is it safe to drive with P24BB?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P24BB fail an emissions test?
Yes, it can. P24BB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P24BB to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P24BB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.