What it means
The exhaust flow control valve A reports a position circuit condition. Exhaust routing for back-pressure or noise control 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 A changes the exhaust path to manage back-pressure or noise, while its position sensor tells the control module where the valve is. The module detects a fault in valve A’s position-sensor circuit, so it cannot reliably use that feedback to confirm the commanded position.
Common causes
Most likely first.
- Position sensor failed
- Wiring or connector fault
Symptoms
- Check-engine light
- Reduced engine power
- Poor acceleration
How to diagnose it
- Read freeze-frame data and the valve A position signal with a scan tool to see when the fault occurs and whether the reported position is missing or implausible.
- With the exhaust cool, inspect valve A’s sensor, connector, and wiring for damage, loose fit, corrosion, or heat exposure.
- Check the sensor’s power, ground, and signal circuits against the wiring diagram and manufacturer’s specification.
- Move the harness gently while watching the live position signal for dropouts that point to an intermittent connection.
- If wiring and connections test correctly, test valve A’s position sensor and replace it only if it fails the manufacturer’s checks.
Common fixes
- Clean and secure valve A’s position-sensor connector.
- Repair damaged or loose wiring in valve A’s sensor circuit.
- Replace valve A’s failed position sensor.
- Repair the connector or terminals if they cannot maintain a reliable connection.
Can I keep driving?
If the engine runs smoothly and power is normal, a short, gentle drive to a repair location may be possible. Avoid hard acceleration; reduced power can make merging or passing unsafe, and continued operation with unreliable exhaust control may worsen drivability 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.