Open or damaged wire in the actuator supply circuit, often due to chafing or corrosion; Poor connection at the ECM connector or at an intermediate connector; Failed actuator (solenoid or relay) that has an internal open circuit, pulling the supply voltage down; Blown fuse or fusible link that feeds the actuator supply circuit; Corroded or loose ground connection for the actuators; Faulty ECM driver circuit (less common)

DTC codes / P06xx · Computer and output circuits / P0657

P0657Actuator Supply Voltage 'A' Circuit/Open

Q: What does code P0657 mean?

Actuator Supply Voltage 'A' Circuit/Open. P0657 means the engine control module (ECM) has detected an open circuit or voltage supply fault on the shared power feed it provides to a group of actuators, such as solenoids and relays. The ECM monitors this actuator supply voltage and sets the code when the voltage on that circuit falls outside the expected range, typically indicating an open connection or a short to ground.

P0657 means the engine control module (ECM) has detected an open circuit or voltage supply fault on the shared power feed it provides to a group of actuators, such as solenoids and relays. The ECM monitors this actuator supply voltage and sets the code when the voltage on that circuit falls outside the expected range, typically indicating an open connection or a short to ground.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Multiple transmission shift issues or harsh shifting if the affected actuators include shift solenoids
Erratic operation of systems powered by the actuator supply, such as variable valve timing or turbo wastegate control
The engine may enter limp mode or have reduced power
In some cases, the vehicle may stall or fail to start if the open circuit affects a critical relay

Common causes, most likely first

Open or damaged wire in the actuator supply circuit, often due to chafing or corrosion
Poor connection at the ECM connector or at an intermediate connector
Failed actuator (solenoid or relay) that has an internal open circuit, pulling the supply voltage down
Blown fuse or fusible link that feeds the actuator supply circuit
Corroded or loose ground connection for the actuators
Faulty ECM driver circuit (less common)

How to diagnose and fix it

Check all fuses related to the actuator supply circuit and replace any that are blown
Inspect the wiring harness for obvious damage, chafing, or corrosion, especially near connectors and heat sources
Disconnect the ECM and the actuators, then perform a continuity test on the supply wire to locate an open circuit
Check for short to ground on the supply wire using a multimeter set to resistance or voltage
Test each actuator individually for internal resistance to rule out a failed component
Clean and tighten ground connections and apply dielectric grease to prevent future corrosion
If all wiring and actuators test good, suspect the ECM and perform a pin-out test or substitute with a known-good unit

What the actuator supply circuit really feeds

P0657 often appears alongside transmission codes like P0700 or P0750 because the actuator supply powers shift solenoids, so a single open circuit can trigger multiple codes.
A common oversight is replacing the ECM when the real problem is a chafed wire behind the engine block or near the exhaust manifold, where heat damage is hidden.
The actuator supply voltage is shared by several components, so a shorted solenoid can pull the entire circuit down and set P0657 even though the solenoid itself is the root cause.
Some vehicles use a relay to feed the actuator supply; a failing relay can cause intermittent P0657 without any visible wiring damage.
P0657 does not always mean the ECM is faulty; in many cases, a simple corroded connector pin is the culprit, so always inspect connectors before condemning the module.

Can I keep driving with P0657?

You can usually drive the vehicle with P0657 set, but if you notice harsh shifting, reduced power, or stalling, limit driving to reach a repair shop. Avoid heavy acceleration or towing until the fault is fixed, as the affected actuators may not function correctly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.