P26C7: Exhaust Flow Control Valve A Control Circuit High

P26C7 is the high-side counterpart: the control line of exhaust valve A carries more voltage than the driver expects, usually because the line touches battery positive or the actuator is damaged. In Ford's 2024 OBD summary it appears as failure type 12 of the valve A check, monitored all the time with a five-second window; the earlier summaries misprint it as P25C7 in their threshold list. Deutz's MD1 list uses it for an exhaust flap whose voltage is too high or shorted. Ford bulletin 25-2146 (Mustang 2018–2023 and Shelby GT500 2020–2022) groups P26C7 with the other flap codes, a lit warning lamp and a mode warning, and directs the technician to inspect the tailpipe actuator and its harness. Unlike P26C6, a high signal can also stem from a wire touching a powered circuit.

Medium severity. Can I keep driving?You can usually keep driving in the short term. If you smell exhaust fumes in the cabin, stop driving and ventilate the car.

Symptoms

Check engine lamp on
Exhaust mode warning in the instrument cluster
No change in exhaust sound between modes

Most likely causes

Control wire shorted to battery voltage or another powered circuit
Defective flap actuator electronics
Missing ground at the actuator pulling the line high

What to check, in order

Start with the simplest. You can tick off each step.

Look for leaks and visible damage
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Check the connectors and wires near the exhaust
Check the live data
Test the actuator with the scanner

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P26C7 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
6: Control modules and outputs
C7: Specific fault in that system

Frequently asked questions

Can I keep driving with code P26C7?

You can usually keep driving in the short term. If you smell exhaust fumes in the cabin, stop driving and ventilate the car.

What causes code P26C7?

The most common causes are: control wire shorted to battery voltage or another powered circuit; defective flap actuator electronics; missing ground at the actuator pulling the line high.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.