What it means
Same as P24B8 with intermittent or erratic signal. The evaporative system captures fuel vapor from the tank and purges it into intake; leaks or stuck purge valves leak hydrocarbons and cause emissions failures.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The leak detection pump pressure sensor tells the control module about pressure changes during an EVAP leak test. P24BC sets when that sensor signal becomes erratic or intermittent instead of remaining consistent with the system's operating state.
Common causes
Most likely first.
- Intermittent contact at connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
How to diagnose it
- Save freeze-frame data and review live EVAP pressure data for sudden jumps, dropouts, or readings that change without a matching test event.
- Inspect the pressure sensor connector and nearby harness for loose terminals, corrosion, chafing, or routing against a vibrating component.
- With live data displayed, gently move the harness and connector to see whether the pressure reading drops out or fluctuates.
- Check the sensor signal, supply, and ground circuits for intermittent opens or poor connections using the wiring diagram and manufacturer's procedure.
- If the circuits remain stable, test the pressure sensor against the manufacturer's specification and replace it if its output is erratic.
Common fixes
- Secure the harness away from vibrating or rubbing parts.
- Repair loose, corroded, or backed-out connector terminals.
- Repair an intermittent open or damaged section of wiring.
- Replace the pressure sensor if its signal remains erratic with sound wiring.
Can I keep driving?
Normal driving is usually possible, but the EVAP leak monitor may not complete and an emissions test may fail. If you notice a persistent fuel smell, arrange prompt inspection.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.