OBD-II code P2671 indicates that the powertrain control module (PCM) has detected voltage higher than the expected calibrated range on the 'Actuator Supply Voltage B' circuit. This circuit provides switched or regulated power to a specific group of actuators (commonly variable valve timing solenoids, cam phasers, throttle body motors, or transmission solenoids, depending on application). The condition is a 'high voltage' fault, meaning the monitored supply is reading above the PCM's accepted window.
A chafed, pinched, or heat-damaged wire in the actuator B supply circuit contacting another 12V source is the most common cause of an over-voltage reading. Inspect harness routing near exhaust manifolds and engine mounts.
Corrosion, spread terminals, or water intrusion at the actuator or PCM-side connector can cause the PCM to see an improper voltage reference on the supply B line.
A solenoid or motor with an internal short to power can pull the supply rail high. Testing each actuator on circuit B individually is required.
Although less typical for a 'high' reading, a compromised sensor or actuator ground on the same circuit can skew the monitored voltage upward.
The PCM's internal driver or regulator for the B circuit can fail in a 'stuck high' state, though this is uncommon compared to harness faults.
A defective PCM is a possible but infrequent cause; it should only be suspected after all external wiring, connectors, and actuators have been ruled out.
Limited driving is usually possible, but the affected actuator(s) may be operating outside their designed range, which can cause poor drivability, increased fuel use, or unintended torque in variable valve timing systems. Have it diagnosed promptly.
No. P2671 is far more often caused by wiring, connector, or actuator problems than by the PCM itself. Replacing the computer first is a common and expensive mistake; the PCM should only be considered after the harness, grounds, and actuators on circuit B have all been verified.
Yes. A failing alternator with voltage spikes or a battery with a poor connection can push supply rails above their calibrated ceiling. Charging system voltage should be checked (typically 13.8–14.7 V running) as part of the diagnosis.
It depends entirely on the vehicle manufacturer and model. Common assignments include VVT/cam phaser solenoids, intake manifold runner controls, electronic throttle components, or transmission shift solenoids. The vehicle-specific service information should be consulted to identify exactly which components are on circuit B.