What it means
Compressor outlet valve mechanically stuck open — boost pressure leaks back to intake before reaching the cylinders, causing under-boost.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The compressor outlet valve opens to release boost pressure when the throttle closes and should close when boost is needed. The control module detects that the valve is not closing as expected, setting this code; a valve held open can let boost escape and reduce engine power.
Common causes
Most likely first.
- Diaphragm torn or seat eroded
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check engine light on
- Reduced engine power or poor acceleration
- Possible underboost
How to diagnose it
- Check freeze-frame data and live boost-related readings for signs of underboost, and note any related turbocharger codes.
- Inspect the valve body, hoses, and connections for leaks, loose fittings, or visible damage that could mimic a valve fault.
- Check that the compressor outlet valve moves freely and that its seat and diaphragm show no visible damage.
- Look for carbon or debris preventing the valve from closing, following the manufacturer's inspection procedure.
- If the valve moves and seals correctly, check the control circuit and commanded operation before replacing parts.
Common fixes
- Reconnect or replace a leaking or damaged valve hose.
- Remove contamination that prevents the valve from closing, if the manufacturer permits cleaning.
- Replace a valve with a torn diaphragm, damaged seat, or excessive mechanical play.
- Repair any confirmed control or wiring fault affecting valve operation.
Can I keep driving?
You may be able to drive gently to a repair location if the engine remains stable, but avoid hard acceleration, towing, and fast merges. Continued boost leakage can reduce power and worsen fuel use.
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.