P0659 — Actuator Supply Voltage "A" Circuit High

OBD2 code P0659 flags a problem with the sensor and actuator circuits (actuator supply voltage "A" circuit high). The car is usually drivable while you plan the repair. Common culprits: faulty sensor or actuator of the affected circuit, poor ground connection, control module driver fault.

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0659 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the actuator supply voltage "A" for damage, corrosion, chafing or poor contact.
Subsystem check With the actuator supply voltage "A" disconnected, measure signal voltage at the harness connector: a high reading with the component unplugged indicates a short to power in the harness; if it drops to normal, the component itself is faulty.
Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0659 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0659 (parts and labor, USD, independent shop rates): Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000; Repair wiring or connectors: $80–$250. Overall, fixing P0659 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Is it safe to drive with P0659?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How do I diagnose P0659 myself?

Start with a scan: confirm P0659, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the actuator supply voltage "A", and verify the suspect component against live data before buying parts.

What is the most common cause of P0659?

The most common causes are: faulty sensor or actuator of the affected circuit, poor ground connection, control module driver fault.

Will P0659 clear itself?

Sometimes P0659 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What are the symptoms of P0659?

Drivers most often notice: possible limp mode depending on the affected component, the affected system operates intermittently or not at all, Check Engine Light on, increased fuel consumption in some cases.

When your vehicle's engine control unit detects that the voltage on the actuator supply voltage "A" circuit exceeds the normal operating range, it logs trouble code P0659. This specific fault relates to a power feed that supplies various sensors and actuators managed by the PCM. The term "circuit high" tells you the module is reading a voltage value that sits dangerously close to full battery voltage on a circuit that should normally carry a much lower reference signal. That unexpected high reading usually stems from one of three root causes: the wiring has shorted directly to a constant power source, a ground path has opened and disrupted normal circuit behavior, or a failed component is forcing the signal line upward.

The PCM constantly watches this supply circuit while the engine runs. It does not trigger P0659 on a single bad reading. Instead, the control module requires the anomaly to appear consistently across multiple drive cycles before it commits the code to memory and illuminates the Check Engine light. When P0659 is stored, the PCM also captures freeze frame data — a snapshot of engine rpm, load, temperature, and vehicle speed at the exact moment the fault was detected. That snapshot becomes your most valuable starting point because it reproduces the conditions that caused the failure.

Symptoms of P0659

P0659 affects a power supply circuit, so symptoms vary depending on which actuator or sensor loses proper voltage regulation:

Check Engine Light remains illuminated after startup
The affected component may stop functioning entirely or operate only intermittently
Some vehicles enter limp mode, limiting power and torque to protect drivetrain components
Fuel economy may decrease noticeably during the period the fault is active
In rare cases, hard starting or stalling occurs if the fault involves a critical engine sensor
A disabled auxiliary system such as exhaust gas recirculation or variable valve timing may accompany the code

Common Causes

The most probable culprits for P0659 are wiring-related issues at the top of this list, followed by component failures:

Actuator supply voltage "A" circuit shorted directly to battery positive somewhere in the harness
Open or interrupted ground return path for the affected circuit
Corroded, loose, or physically damaged connector that disrupts voltage regulation
Faulty sensor or actuator pulling the signal line above its intended operating voltage
Blown fuse feeding the actuator supply voltage "A" circuit
Control module internal driver failure that misreads the circuit state
Poor chassis ground connection causing voltage anomalies throughout the circuit

Diagnostic Procedure

Follow these steps in order to isolate the root cause without replacing unnecessary parts:

Connect a quality OBD2 scanner and confirm P0659 is actively stored. Record all freeze frame data and any related pending or permanent codes that accompanied it.
Search for technical service bulletins tied to your specific make, model, and model year. Many manufacturers have published fixes or software updates for recurring P0659 faults.
Perform a thorough visual inspection of the wiring harness and connectors associated with the actuator supply voltage "A" circuit. Look for melted insulation, broken strands inside the wire, corrosion buildup, and any signs of water intrusion at connectors.
Disconnect the suspect component and measure voltage at the harness side of the connector with a multimeter. A high reading with the component unplugged confirms a short to power inside the harness. If the reading drops to normal reference voltage, the component itself has failed internally.
With the component still disconnected, verify ground continuity, check for unwanted resistance, and wiggle-test the harness while monitoring live data for signal dropouts that indicate hidden wire breaks.
Reassemble everything, clear the code, and complete a drive cycle that reproduces the exact conditions captured in the freeze frame data. Verify P0659 does not return before considering the repair complete.

Repair Options and Costs

Depending on what your diagnosis uncovers, here are the typical repair paths and their costs at independent shop labor rates:

Wiring repair or connector replacement: $80–$250
Replacement of faulty sensor or actuator: $150–$500
Control module diagnosis and repair: $300–$1,000

Labor rates vary by region, and module repair sometimes requires dealer-level programming that adds to the final bill.

Total Cost Summary

Most P0659 repairs fall somewhere between the wiring repair end and the sensor replacement end of that range. A professional diagnosis that correctly identifies the problem before you purchase parts is the single most effective way to avoid overspending. The worst-case scenario — a failed control module requiring replacement or factory reprogramming — represents a small fraction of reported cases, so investigate cheaper possibilities thoroughly before committing to that expense.

Can You Drive With P0659?

The severity rating for this code is short, meaning most vehicles remain driveable when P0659 is active. You may experience reduced performance or lose function of one auxiliary system, but core engine operation typically continues. However, if the fault causes intermittent stalling, prevents the engine from starting, or triggers warnings related to braking or steering systems, stop driving and address the issue immediately. Otherwise, schedule diagnosis and repair at your earliest convenience to prevent the problem from worsening.