What it means
The exhaust flow control valve C reports a position circuit low 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 sends the control module a signal representing valve position. This code sets when that signal voltage is lower than the module's allowed range, which can happen if the signal wire is grounded, the sensor is internally shorted, or a corroded connection disrupts the circuit.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Change in exhaust sound
- Reduced engine performance
How to diagnose it
- Record freeze-frame data and check live valve C position data for a low, fixed, or implausible reading.
- With the exhaust cool, inspect valve C's position sensor connector and wiring for corrosion, rubbed-through insulation, or contact with ground.
- Check the sensor's reference supply and ground, then measure its signal circuit as described by the manufacturer's specification.
- With the circuit safely isolated as specified by the manufacturer, check whether the signal wire is shorted to ground.
- If the wiring and connector pass, test the valve C position sensor and replace it only if its output remains low under the specified test.
Common fixes
- Clean and secure corroded valve C sensor connector terminals if they remain serviceable.
- Repair a signal wire shorted to ground or other damaged wiring in the valve C position circuit.
- Replace the valve C position sensor if it is internally shorted.
- Replace the valve assembly if the position sensor is not separately serviceable and tests confirm its failure.
Can I keep driving?
If the vehicle has no severe power loss, a gentle drive to arrange repair may be possible. Avoid heavy loads because the module may not know valve C's position, which can affect exhaust control 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.