What it means
A general circuit fault on the secondary EVAP system pressure sensor or switch B. 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. The module checks its electrical signal, and this code sets when the B circuit has a general fault that prevents a reliable pressure reading.
Common causes
Most likely first.
- Open or short in pressure sensor wiring
- Faulty pressure sensor or switch
- Loose or corroded connector
- Pressure-sensing hose restricted or disconnected
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 EVAP pressure readings to see when sensor B's signal became unreliable.
- Inspect pressure sensor or switch B's connector and wiring for corrosion, loose pins, or damage.
- Check the pressure-sensing hose to sensor B for a disconnection, kink, blockage, or crack.
- Test the B circuit for opens and shorts and verify its power and ground where applicable.
- Compare sensor B's signal and pressure reading with the manufacturer's specification during the specified EVAP test.
Common fixes
- Reconnect or replace a damaged pressure-sensing hose to sensor B.
- Clean and secure the sensor B connector.
- Repair an open or short in the B-circuit wiring.
- Replace pressure sensor or switch B if its reading remains faulty with a sound circuit.
Can I keep driving?
The vehicle is usually driveable, but an EVAP fault can increase fuel-vapor emissions and cause an inspection failure. If you smell fuel strongly or see a fuel leak, stop driving and address that promptly.
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.