P0659
UniversalThe Powertrain Control Module (PCM) or Engine Control Module (ECM) detects an abnormally high voltage reading in the circuit that supplies power to one or more actuators.
Medium SeverityThis code indicates that the actuator supply voltage circuit is sending a higher than expected voltage to various vehicle actuators. This can lead to erratic operation or damage to the affected actuators, potentially causing issues with engine or transmission performance.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical diagnostic or repair work to prevent accidental shocks or damage to electronic components. Be cautious when working around hot engine components or moving parts.
Common Symptoms
- Check Engine Light illumination
- Erratic operation of various vehicle systems
- Rough idle or stalling
- Engine performance issues (e.g., poor acceleration, misfires)
- Transmission shifting problems
- No visible symptoms other than the illuminated MIL (Malfunction Indicator Lamp)
Common Causes
- Short to voltage in the actuator supply circuit
- Faulty actuator causing a voltage feedback
- Damaged or corroded wiring or connectors
- Faulty Powertrain Control Module (PCM) or Engine Control Module (ECM)
- Incorrectly installed aftermarket accessories affecting the circuit
Frequently reported on: General/Universal
Diagnostic Steps
- Inspect all wiring and connectors associated with actuator circuits for damage, corrosion, or loose connections. Pay close attention to any areas where wires might be pinched or chafed.
- Using a digital multimeter, test the voltage at the actuator supply circuit. Compare the reading to vehicle specifications; it should typically be around 5V or 12V depending on the system.
- Check for Technical Service Bulletins (TSBs) related to this code for your specific vehicle make and model, as manufacturers may have known issues or updated diagnostic procedures.
- If equipped, test individual actuators that receive voltage from the affected circuit for proper operation and internal resistance.
- If all other checks are inconclusive, and wiring is confirmed good, a faulty PCM/ECM may be the cause, but this should be a last resort after thorough diagnosis.
👨🔧 When to Call a Professional
If basic visual inspection and multimeter checks do not quickly pinpoint a wiring issue or a specific faulty actuator, or if you suspect a problem with the PCM or ECM itself, it is best to consult a professional mechanic. Electrical diagnostics can be complex and require specialized tools.
Commonly Asked Questions
What does Actuator Supply Voltage Circuit High mean?
It means the vehicle's computer (PCM/ECM) has detected that the electrical circuit providing power to one or more actuators is receiving a voltage that is higher than its normal operating range.
Can I drive with a P0659 code?
While the car might still drive, it's not recommended for long. A high voltage can damage sensitive actuators or the PCM/ECM over time, potentially leading to more severe and costly repairs or unexpected vehicle behavior.
What is an actuator in a car?
An actuator is a component that controls a mechanical action in response to an electrical signal from the vehicle's computer. Examples include throttle body actuators, variable valve timing (VVT) actuators, and wastegate actuators.
How do I test the actuator supply voltage circuit?
You will need a digital multimeter. With the ignition on (engine off or running, as specified by a repair manual), carefully back-probe the circuit at the PCM or at the actuator connector to measure the voltage and compare it to the manufacturer's specifications.
Is a P0659 code always a wiring problem?
Not necessarily. While wiring issues like a short to voltage are common causes, a faulty actuator itself could be feeding back high voltage, or in rare cases, the PCM/ECM could be internally shorted, causing the high voltage output.