What it means
Same as P24D5 with the signal voltage below the plausible range. 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
EVAP pressure sensor or switch B monitors pressure in a secondary part of the fuel-vapor control system. This code sets when the B-circuit signal falls below the module's plausible range, often because the signal is shorted to ground or the circuit has a poor connection.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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
- Review freeze-frame data and live sensor B voltage to confirm the signal is below range.
- Inspect the B sensor connector and harness for corrosion, moisture, chafing, or a signal wire touching ground.
- Check the sensor B circuit's power and ground, where applicable, against the wiring diagram.
- Measure the signal at sensor B and at the module side of the circuit to locate excessive voltage drop or a short to ground.
- If wiring checks pass, test pressure sensor or switch B against the manufacturer's specification.
Common fixes
- Clean and secure a corroded sensor B connector.
- Repair a signal wire shorted to ground or damaged by chafing.
- Restore a poor power or ground connection in the B circuit.
- Replace pressure sensor or switch B if it produces a low signal with a sound circuit.
Can I keep driving?
The vehicle is usually driveable, but the EVAP system may not monitor fuel-vapor pressure correctly and emissions inspection can fail. Stop if there is a strong fuel smell or a visible leak.
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.