What it means
On engines that have a separate high-load purge line - to use boost pressure to pull vapor on turbo applications - the ECU monitors flow when this path is commanded. The flow is below the expected level - the venturi, line, or check valve is restricted, or the line is incorrectly routed.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
A high-load EVAP purge path lets boost on turbocharged engines help draw fuel vapour from the charcoal canister into the engine. The ECU checks whether vapour flow through purge line A reaches the expected level when this path is commanded; restricted flow can point to a blocked venturi or hose, a faulty check valve, or incorrect hose routing.
Common causes
Most likely first.
- Restricted high-load purge line
- Blocked or restricted venturi
- Sticking or faulty check valve
- Incorrectly routed or damaged purge hose
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
- Save freeze-frame data and check EVAP purge commands and related live data to see when the high-load path was expected to flow.
- Inspect the high-load purge hose for kinks, damage, disconnection, or routing that differs from the vehicle diagram.
- Check the line and venturi for restrictions, following the manufacturer's procedure to avoid damaging EVAP components.
- Test the check valve for correct direction and operation against the manufacturer's specification.
- If the path is clear and correctly routed, use the manufacturer's test procedure to verify flow when the ECU commands high-load purge.
Common fixes
- Correct misrouted or disconnected high-load purge hose.
- Replace a damaged or kinked hose.
- Clear or replace a restricted venturi.
- Replace a sticking or faulty check valve.
Can I keep driving?
The fault usually does not cause limp mode, but fuel vapour control and emissions performance can suffer. Avoid ignoring a persistent fuel smell, and arrange diagnosis soon, especially before an emissions inspection.
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.