What it means
During the leak-detection self-test, airflow through the reference orifice is above the expected rate — typically a leak around the orifice or a damaged seal.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The EVAP leak-detection system measures airflow through a calibrated reference orifice during its self-test. P043F means the measured flow is higher than expected, which can point to leakage around the orifice or its seal, damaged plumbing, or an airflow measurement or pump fault.
Common causes
Most likely first.
- Leak around the reference orifice or its seal
- Damaged or displaced seal
- Cracked or loose leak-detection plumbing
- Fault in the leak-detection pump or airflow measurement
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
- Confirm P043F and check freeze-frame data and related EVAP codes for clues about when the reference-flow test failed.
- Check that the fuel cap is correctly fitted and inspect accessible leak-detection hoses for loose connections, cracks, or displaced fittings.
- Inspect the reference-orifice assembly and seal for damage, poor seating, or signs of leakage, using the vehicle's service information.
- Run the EVAP leak-detection test with a scan tool if available and observe whether the pump and airflow readings behave as expected.
- If the orifice and plumbing are intact, test the pump and airflow measurement system according to the manufacturer's procedure.
Common fixes
- Refit or replace a damaged fuel cap.
- Reseat or replace a displaced or damaged reference-orifice seal.
- Repair cracked or loose leak-detection plumbing.
- Replace a faulty pump or airflow measurement component if it fails the manufacturer's test.
Can I keep driving?
The code generally does not affect how the vehicle drives, but emissions testing may fail. If you smell fuel, avoid flames and other ignition sources nearby; have a persistent or strong smell investigated 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.