What it means
The exhaust aftertreatment fuel-air purge valve control circuit signal is below the expected range. The code does not by itself identify the cause or valve state.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The purge-valve control circuit switches the exhaust aftertreatment fuel-air valve. P24FA means the circuit signal is lower than expected, which can result from a grounded control wire, a driver held on, or excessive resistance at a connection; it does not by itself prove the valve is stuck open.
Common causes
Most likely first.
- Control wire shorted to ground
- Failed low-side driver stuck on
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Aftertreatment warning light
- Reduced engine power or performance
- Increased exhaust emissions
How to diagnose it
- Record freeze-frame data and check whether the fault occurs during a valve command or at key-on.
- Inspect the purge-valve connector and control-wire routing for corrosion, rubbed-through insulation, or contact with ground.
- With the circuit isolated as specified by the manufacturer, check whether the control wire is shorted to ground.
- Measure connector contact condition and valve-coil continuity against the manufacturer's specification.
- If the harness and valve pass, use the manufacturer’s scan-tool procedure to check whether the dosing module’s low-side driver is stuck on.
Common fixes
- Clean and secure corroded or loose connector terminals.
- Repair the control wire where it is shorted to ground.
- Replace the valve if its coil or internal connection is faulty.
- Repair or replace the dosing module if testing confirms a failed low-side driver.
Can I keep driving?
Limit driving and avoid heavy loads because the purge valve may not be controlled correctly and emissions can increase. Stop if the vehicle loses significant power or displays a stop-driving warning.
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.