P24B8 code meaning
EVAP System Leak Detection Pump Pressure Sensor Circuit
Powertrain system Generic code P24xx codes Check engine light
What P24B8 means
P24B8 is the general circuit fault of the pressure sensor that sits inside an evaporative leak check module together with the pump and the switching valve. The sensor gets a 5 V reference from the engine computer and reports canister-side pressure during the engine-off leak test. No manufacturer documents P24B8 publicly; GM, Mitsubishi and Subaru use the more specific P24B9 to P24BB for this sensor. CARB requires such EVAP input components to be checked for circuit faults and implausible values. With this fault present, the leak test cannot be trusted and will not complete, so the EVAP readiness flag stays open. Typical findings are a broken reference or ground wire, a corroded module plug or a failed module.
P24B8 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 P24B8
- Malfunction indicator lamp on
- EVAP readiness monitor does not complete
Common causes of P24B8
- Most likelyOpen or shorted 5 V reference, ground or signal wire to the leak check module
- PossibleCorroded or loose connector at the leak check module near the canister
- PossiblePressure sensor inside the leak check module failed
- Less likelyEngine control module does not supply the sensor reference
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 P24B8 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). |
| B8 | The exact fault in that area. |
What to do next
- Note P24B8 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 P24B8
What does P24B8 mean?
P24B8 means "EVAP System Leak Detection Pump Pressure Sensor Circuit". P24B8 is the general circuit fault of the pressure sensor that sits inside an evaporative leak check module together with the pump and the switching valve. It is a generic code, so it means the same on every make.
Is it safe to drive with P24B8?
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 P24B8 fail an emissions test?
Yes, it can. P24B8 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 P24B8 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 P24B8 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.