P24B9: Evaporative Emission System Leak Detection Pump Pressure Sensor Circuit Range/Performance

What it means

Same as P24B8 with the signal in plausible range yet not matching the pump operating curve. 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 evaporative system leak detection pump creates pressure or vacuum so the control module can check for vapor leaks. Its pressure sensor reports the result, and this code sets when the signal remains electrically plausible but does not follow the expected pressure change as the pump operates.

Common causes

Most likely first.

1. Pressure sensor drift or failure
2. Restricted or leaking pressure-sensing hose
3. Loose or corroded connector
4. Leak detection pump not producing expected pressure

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

1. Save freeze-frame data and check for related evaporative codes that may point to a leak or pump issue.
2. Inspect the pump pressure sensor connector and wiring for corrosion, loose pins, and harness damage.
3. Check the pressure-sensing hose for restrictions, leaks, kinks, or disconnection that could distort the sensor reading.
4. Compare live pressure sensor data with pump operation during the manufacturer's specified test to see whether the signal follows the expected trend.
5. Test the pressure sensor and leak detection pump separately using the manufacturer's procedure.

Common fixes

• Reconnect or replace a leaking, kinked, or restricted sensing hose.
• Clean and secure the pressure sensor connector or repair damaged wiring.
• Replace the pressure sensor if its readings drift despite a sound hose and circuit.
• Repair or replace the leak detection pump if it fails to produce the expected pressure change.

Can I keep driving?

You can generally continue normal driving if there is no fuel smell or other problem, but plan a repair before an emissions test. A faulty pressure reading can keep the vehicle from detecting evaporative leaks.