What it means
Voltage on the exhaust flow control valve A control line is below the expected window. The exhaust control valve modulates exhaust backpressure or routing (EGR feed, sound, regen support); a malfunction shifts torque mapping and may trigger limp mode.
At a glance
- Usually lights the check-engine light
How it works
Exhaust flow control valve A regulates exhaust routing or backpressure for systems such as EGR feed, exhaust sound, or aftertreatment heating. P26C6 sets when the valve A control line voltage falls below the controller’s expected range, often because the line is grounded or the solenoid circuit is drawing abnormal current.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in solenoid coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may be on
- Reduced engine power or altered response
- Exhaust or engine sound may change
- Emissions warning may appear
How to diagnose it
- Scan for related exhaust control codes and review freeze-frame data to see when valve A circuit voltage was low.
- Inspect valve A wiring and connector for chafing against ground, water intrusion, corrosion, or pushed-back terminals.
- With the circuit safely isolated as specified by the manufacturer, check the valve A solenoid for an internal short against its specification.
- Test the control wire for an unintended short to ground and check connector contact condition along the circuit.
- If the valve and wiring pass, test the controller output using the manufacturer's procedure.
Common fixes
- Clean and secure corroded or loose valve A connector terminals.
- Repair control wiring shorted to ground or damaged by chafing.
- Replace valve A if its solenoid is internally shorted.
- Repair the controller circuit if testing confirms its output is faulty.
Can I keep driving?
If the vehicle has reduced power or an exhaust or emissions warning, avoid heavy acceleration and towing until the fault is fixed. Continued operation with valve A incorrectly controlled can affect exhaust flow and aftertreatment performance.
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.