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Code P0444. Causes, Symptoms, Diagnosis and Repair

The P0444 code is identified as “Evaporative Emissions Control System (EVAP) Purge Control Valve Circuit Open.” It is a generic code that is activated when a fault is located in your car’s EVAP system.

This code indicates that part of the EVAP control system no longer works correctly. The EVAP system consists of many components, most of them belonging to another very important system: the fuel system.

Operation of the EVAP Evaporative Emissions System

The emissions control system (EVAP) Prevents fuel vapor from escaping from your car’s fuel system. Fuel vapors are sent through hoses to a charcoal container while the car is off.

When the engine is running, the purge control valve opens, allowing fuel vapors to enter the fuel supply system under vacuum, thus being used by the engine.

The P0444 fault code can be defined as EVAP System Purge Control Valve Open Circuit. It means that there is an excessively low voltage signal being sent to the PCM through the valve.

The EVAP canister purge is controlled by a valve that allows fuel vapors to enter due to the vacuum created by engine operation. They flow from the fuel tank into the engine for combustion, rather than escaping into the atmosphere.

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What is Code P0444?

Error code P0444 is defined as Evaporative Emission Control System Purge Control Valve Open Circuit. That is, too low a voltage signal is sent to the PCM through the valve.

For vehicles with EVAP (Evaporative Emission Control Systems), the engine draws fuel vapors through the gas tank that would otherwise be vented to the atmosphere.

Fuel vapor is directed through a vacuum line to the engine inlet, while the purge valve or solenoid measures the anticipated level of fuel vapors.

All of this is controlled by the PCM (powertrain control module). The PCM checks the purge control valve voltage and if it cannot detect the change with the purge valve activated, it will trigger error code P0444.

Symptoms of Code P0444

You can find several symptoms related to the code P0444. However, in most cases, only the Check Engine light activates. Or there may be other symptoms, but the driver does not notice them.

Let’s look at some of them:

  1. MIL light activated on the control panel. Also known as “Check Engine”.
  2. The lean mixture in the engine.
  3. Irregular idle.
  4. Difficult start.
  5. Excessive pressure in the gas tank in the form of a “hissing” sound when removing the cap.
  6. A slight increase in fuel consumption.
  7. Noticeable fuel odor caused by released fuel vapors.
  8. The engine stalls or hesitates.

In most cases, the vehicle will show no noticeable conditions related to the vehicle’s drivability.

There may be a slight increase in fuel consumption, but the error code will not affect engine performance at cruising speed.

Possible Causes of Code P0444

Error code P0444 It can be caused by the following:

  • Internal short circuit or breakage of the purge valve.
  • Breakage in the wiring harness.
  • Loose or disconnected wiring harness.
  • Connector shorted.
  • Corrosion in the connector.
  • Purge the solenoid valve open or short circuit.
  • The controller circuit inside the PCM module is defective.
  • Damaged PCM.

How to Diagnose Code P0444

As with most fault codes, the code P0444 can be identified with the use of an OBD-II scanner.

Scan the car

  1. Connect the scanner to the car to detect the P0444 code and any others that are activated.
  2. Then erase the codes with the help of the tool and perform a test on the car, turning on the engine for about 15 minutes.
  3. If the code does not appear, you may have an intermittent problem.
  4. If the code appears again, you should check the evaporative emissions system.

Visual inspection

  1. You must start your diagnosis by checking all the components and lines related to the EVAP system. You should look for signs of wear, damage, and/or disconnection within the lines.
  2. With the vehicle running, you can identify a possible vacuum leak simply by listening to the abnormal sucking sound of the vacuum lines.
  3. Some technicians use a smoke machine to fill the EVAP system with smoke and find a leak through a visual indication of smoke escaping.
  4. If this is your case, you should take the car to a workshop where this type of diagnosis is available.

Test the purge valve

  1. Use a diagnostic tool such as the OBD2 scanner to activate the bleed valve. Listen for a click from the purge solenoid. You must click once, and on some models, you can click again.
  2. If it does not click when you activate the scan tool, disconnect the connector and check the solenoid and connector for damage.
  3. Then check the battery voltage on the lead wire with the key in the ON position, but without starting the car.
  4. If there is voltage, ground the contact manually with a jumper and see if the valve clicks. If so, the solenoid is working properly, but there is a problem with the control circuit.
  5. If the valve does not click when you make the manual connection, the purge solenoid is damaged and should be replaced.

Test the control circuit

  1. To check for a problem in the control circuit, reconnect the solenoid and disconnect the ground wire from the connector.
  2. With the ground wire disconnected from the controller, turn the key to ON and manually ground the purge valve control wire.
  3. The solenoid should click, so there is no problem with the control cable to the solenoid and there is a problem with the ECM purge valve actuator circuit.
  4. If it doesn’t click, then there is a break in the wiring between the ECM and the solenoid.

How to Fix Code P0444

The repairs you decide to make should be based on the results of your diagnosis. Repairs for this error code are fairly simple and straightforward, but the success of the repair largely depends on the diagnosis.

The EVAP system should be thoroughly checked before proceeding with any repair procedures.

  1. Broken or faulty wiring should be repaired, if not replaced as necessary.
  2. Defective components in the EVAP system must be replaced after diagnosis.
  3. Repair of damaged EVAP system lines.
  4. Purge Solenoid Voltage Supply Circuit Repair.
  5. PCM control circuit repair.
  6. Replace the purge solenoid valve.
  7. Repair or clean the connector.
  8. Replace the PCM.
  9. The system should be retested after each repair to limit unnecessary troubleshooting.
  10. The vehicle should be taken for a test drive after the repair to ensure the problem is resolved and does not return.

This error code can be quite complicated to resolve, as sometimes the problem is not with the EVAP itself, but with a vacuum leak somewhere else. That is why it is important to diagnose thoroughly.

Simple cases may cause symptoms of this error code. Many people mistakenly replace some parts of the EVAP that actually work correctly.

Therefore, be sure to check the vacuum lines and fuel caps beforehand to rule out the possibility of the problem.

Replacing Components To Repair Code P0444

  1. Charcoal container: OBD code P0444 may appear due to a faulty charcoal canister. If there is any vacuum leak in it, you should replace it.
  2. Evaporator purge valve: It is not as common as many believe, but if it fails, it triggers the P0444 code. Its replacement is somewhat difficult due to its location and access.
  3. Purge solenoid: The purge solenoid is more likely to be damaged than the valve itself. If the diagnosis indicates a failed solenoid, you must replace it.

Common Errors When Diagnosing Code P0444

Most people assume that there is surely something wrong with the EVAP system, but in reality, there could be a vacuum leak from the carbon canister to the engine.

These types of leaks result in the activation of a P0444 code.

If the fuel cap is not tightened correctly, it can also cause the symptoms of code P0444. For this reason, EVAP parts are sometimes replaced without failure. Fortunately, checking and adjusting the lid properly is free.

You must make a good diagnosis and rely on its results to carry out any repair.

Is Code P0444 Serious?

No, this code really does not pose a risk to the driver or the car. Most of the time, even the driver does not notice the fault, except for the Check Engine light being activated.

A car with a code P0444 activated, will not be able to pass the emissions test, so if you have one planned, you will need to resolve this first.

If the fault worsens, you may detect the smell of fuel, a slight increase in fuel consumption, an idle that is somewhat different than usual, and of course, the check engine light will remain activated.

We recommend that you carry out the repair as soon as possible so as not to aggravate the conditions of your car.

How to Avoid Code P0444?

Electrical failures are difficult to avoid since components can stop working for multiple reasons associated with operating conditions.

However, if you perform periodic checks, you will be able to detect damaged cables or loose connections that can activate fault codes. Good preventive maintenance and routine check-ups are the most recommended.


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The P0444 code It is one of the few faults that does not affect the drivability of your car. Its symptoms are very mild, almost imperceptible, only noticeable when it worsens.

If you detect this code on the road when performing a scan, you can continue driving, reach your garage without problems, and take matters into your own hands calmly.

Do not wait too long to repair this code, do not let the failure get worse.

If you want to know other articles similar to Code P0444. Causes, Symptoms, Diagnosis, and Repair you can visit the category Fault Codes.


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