What it means
The exhaust flow control valve C reports a position circuit range/performance condition. Exhaust routing for back-pressure or noise control on this branch cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The position sensor on exhaust flow control valve C reports how far the valve has moved. The control module checks whether that reading is plausible and tracks the valve's movement; this code sets when the signal is outside its expected range or does not correspond to the valve's actual movement, such as when the linkage is loose or the sensor has drifted.
Common causes
Most likely first.
- Sensor offset drifted
- Linkage between sensor and valve loose
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light
- Change in exhaust sound
- Reduced engine performance
How to diagnose it
- Record freeze-frame data and compare live commanded and reported positions for valve C to identify when the reading becomes implausible.
- With the exhaust cool, inspect valve C's linkage and sensor coupling for looseness, wear, or movement that does not match the valve.
- Inspect the position sensor connector and wiring for damage or poor connections that could distort the reading.
- Use an actuator test, if available, to move valve C through its range while checking whether the position signal changes smoothly and consistently.
- If the linkage and wiring are sound, evaluate the sensor's readings and calibration against the manufacturer's procedure.
Common fixes
- Secure or repair a loose valve C linkage or sensor coupling.
- Repair poor connections or damaged wiring at the valve C position sensor.
- Replace a position sensor that fails the manufacturer's range or response checks.
- Replace a worn valve C assembly if its mechanism or sensor mounting cannot maintain accurate position feedback.
Can I keep driving?
If performance remains normal, limit driving to what is needed for diagnosis and avoid heavy loads. Inaccurate position feedback can prevent correct exhaust routing and may worsen performance or emissions.
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.