Error Code P0659 is defined as Actuator Supply Voltage A Circuit High. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, particularly those made since 1996 up to present. This includes models from, but not limited to Chevrolet, Chrysler, Dodge, Honda, Nissan, Toyota, etc. Specifications on the definition, troubleshooting, and repairs, of course, vary from make, model, and powertrain configuration.

The PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) is responsible for a lot of things, including monitoring and adjusting multiple actuators, sensors, solenoids, valves, etc. It also makes sure that all these and other components are working seamlessly and in conjunction to meet the desired values for the vehicle’s operation and fuel efficiency. Thus, when this code appears, depending on the make and model of the vehicle, drivers may experience transmission drivability issues.

For European model vehicles, this code is an EVAP diagnostic code. To ensure proper diagnostic direction, it’s extremely important to refer to the service manual. Many times, the symptoms are strong indicators of what component or system you will be working on directly to fix the problem.

In terms of Error Code P0659 and other related codes, the PCM has determined an abnormal value within the actuator supply voltage circuit. This means there’s an abnormality in comparing the actual values to desired ones. If the values are outside the desired range, it lights up the Check Engine light and registers the code.

It’s important to research the designation for “A” within the circuit. Depending on the make and model, this could designate a certain wire, harness, location, etc. With this, OEM (original equipment manufacturer) technical service information must always be used.

Depending on the description of the particular make and model, the TCM (transmission control module) could detect this code.

Error Code P0659 (Actuator Supply Voltage A Circuit High) is active when the ECM or TCM has detected a high voltage situation within the actuator supply voltage “A” circuit

Common Symptoms

When this code appears you can expect poor overall drivability for the vehicle. Other common symptoms include:

  • Lack of torque
  • Poor shifting
  • Limited power output
  • Poor fuel mileage
  • Stuck in gear
  • Poor fuel mileage
  • Abnormal engine revving/speeds

Possible Causes

Open or shorted circuit is the most common cause of this code. Other common causes include:

  • Open or shorted circuit between two interlacing supporting control modules
  • Open or shorted circuit between engine sensors and PCM
  • Disconnected ground wire running to a control module
  • Internal malfunction in the PCM
  • Water intrusion
  • Short to power
  • Broken/melted connector(s)

General electrical problem such as wrong battery, charging system issue, etc.

How to Check

As with most trouble codes, the first step in diagnosing this code is searching the TSB (technical service bulletin) for known issues with the specific vehicle.

Advanced diagnostic steps are vehicle specific, and usually, require advanced equipment and the right knowledge to be performed accurately. This entry will talk about the basic steps, but make sure you refer to the TSB for the specific year, make, model, and powertrain configuration for the specific guide.

Step 1

Start by clearing the codes with the scanner and take the vehicle for a test drive to see if the code comes back. If the code comes back, locate the right circuit/harness that you must work with, check it for signs of damages. This could be routed under the vehicle where road debris, dirt, ice, etc., can cause damages. Any open or chafed wires must be repaired.

It’s also a good idea to check the connectors involved. Disconnect and inspect the pins, look for signs of damage such as bent ones, as these could cause electrical issues. Sometimes high resistance within a circuit can cause excessive heat that can burn through the insulation. If you find damage, then there’s a good sign it’s what is causing the problem.

Note: Make sure you solder and shrink wrap any damaged wires, especially those that are subjected to elements. Replace connectors with OEM to ensure proper electrical connections.

Step 2

Use the service information to look for the actuator. These can be externally accessed. If so, in your case, you could verify the integrity of the actuator itself. Desired values for the test vary significantly, so make sure your multimeter and service manual are ready. Avoid unnecessary damages to the connections by using the right test pin connectors. If the recorded values are outside the desired ones, the sensor can be deemed defective and must be replaced with a new one.

Step 3

Inspect your PCM and TCM, look for signs of damage. They are usually located where water intrusion is susceptible, which could lead to corrosion. If you see any green powder, then that’s a red flag for damage. In this case, you should see a qualified technician to a more thorough diagnosis of your vehicle.

How to Fix

Depending on your diagnosis, common repairs for this code include:

  • Repair or replacement of PCM
  • Repair or replacement of supporting control module
  • Replacement of defective connections between control modules
  • Replacement of damaged or missing wires surrounding the “A” area of the circuit

This article is strictly for information purposes only, and the technical data and service bulletins for your specific vehicle should always take precedence.

Note that, the severity of the problem varies greatly; it’s entirely possible for a vehicle with this code not to have any noticeable symptoms. Most vehicles, however, will experience symptoms severe enough to keep the vehicle from starting. Also, even if the vehicle could run, it’s crucial to have this code addressed as soon as possible to minimize the risk of further damage.

If the cause of Error Code P0659 is caused by related wiring, mechanics will use OBD-II scanner to determine the source of the problem more efficiently. If the cause if malfunctioning wiring or power input signals, then ask your mechanic about better repair options for the specific model of your vehicle.