What it means
The exhaust flow control valve C reports a position circuit 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
Exhaust flow control valve C uses a position sensor to report how far its valve has moved. The control module monitors that sensor's electrical circuit, and this code sets when the position signal circuit is faulty, so the reported position may be unavailable or unreliable.
Common causes
Most likely first.
- Position sensor failed
- Wiring or connector fault
Symptoms
- Check-engine light
- Change in exhaust sound
- Reduced engine performance
How to diagnose it
- Record freeze-frame data and check live valve C commanded and reported positions to confirm whether the position reading is missing or erratic.
- With the exhaust cool, inspect valve C's sensor connector and nearby wiring for looseness, corrosion, chafing, or heat damage.
- Check the sensor circuit's power, ground, and signal connections against the wiring diagram and manufacturer's specification.
- Move the valve using an available scan-tool actuator test while monitoring the position signal for a response.
- If wiring and connections pass inspection, test the valve C position sensor and actuator assembly according to the manufacturer's procedure.
Common fixes
- Reconnect or repair a loose, damaged, or corroded valve C sensor connector.
- Repair damaged wiring in the valve C position sensor circuit.
- Replace the valve C position sensor if circuit tests confirm it has failed.
- Replace the valve C assembly if the sensor is not serviceable separately and testing confirms an assembly fault.
Can I keep driving?
If there is no major power loss or unusual exhaust behavior, drive gently only as needed to reach a repair location. The module may be unable to control valve C reliably, which can worsen drivability and 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.