There is a delicate balance involved in controlling emissions and allowing the engine to reach peak performance. The EVAP system was invented to help with this effort. Although the EVAP system is not critical to basic vehicle functionality, emissions regulations dictate it must function.

The P0444 check engine light code is one of the many EVAP-related codes that are logged when a component fails. In this guide, we will delve into why this trouble code occurs. Including symptoms, causes, and diagnostic techniques.

What Is the P0444 Code, and What Does It Mean? 

The P0444 code is an “EVAP purge control circuit” code. It means that there is an issue with the evaporative emissions control system or EVAP system, causing the ECU to log a fault with the solenoid.

What Causes the P0444 Code?

Emissions control systems are often one of the first systems to go haywire. Additionally, because they are not mechanical systems or drivetrain-related, issues can pop up and disappear at a whim and be difficult to detect. Some of the major causes are:

• Wiring harness failure
• Fuel system leaks
• Purge control solenoid
• Faulty ECU

Fuel System Leaks

Vacuum leaks will often cause the ECU to log many trouble codes that are related to component failure. The simple reason for this is that changes in air pressure cause environmental changes for sensors that operate in certain conditions.

This can stem from a loose or misplaced fuel cap, damage to the fuel tank, vacuum lines, or even fuel lines.

Purge Control Solenoid

Failure of this solenoid is one of the main causes of the P0444 code. It’s one of the few electronic components in the EVAP system and the only one related to this trouble code. A vacuum line failure on the way to this solenoid can also cause this trouble code.

Wiring Harness Failure

A failure in the wiring harness is always a consideration when dealing with electrical problems. The EVAP solenoid cannot perform correctly if there is a wiring failure, hence the P0444 code when it occurs.

Faulty ECU

ECU failure is rare. Manufacturers specifically design fuses and relays to prevent voltage spikes and overcurrent that may damage the ECU. Still, they can fail and when they do, you can have the P0444 trouble code.

What is a Purge Control Valve Circuit?

This is the circuit that allows fuel vapors collected in the EVAP canister to be released back into the engine. It’s closed when the engine is off, allowing vapors to be collected 

and opened when the engine is turned on. Take a look at our selection of purge control solenoids for a quality replacement!

What Are the Common Symptoms of P0444 Fault Code?

Symptoms for emissions issues are scarce. Air is odorless, and you can’t diagnose a problem based solely on a random gasoline smell. So these symptoms only connect the dots before moving on to more thorough diagnostic techniques. The common symptoms of a P0444 are as follows:

• Check engine light
• Reduced fuel economy
• Excessive gasoline smells
• Poor Starting behavior

Check Engine Light

EVAP codes like the P0444 are enough to trigger a check engine light. It may turn on intermittently depending on the root cause of the problem but as this is a non-serious issue, it will not flash. Either way, don’t ignore it if you see it. 

Reduced Fuel Economy

A reduction in fuel economy is a given when you have the P0444 code. The fuel vapors that would normally be trapped in the EVAP canister and reused are now let into the atmosphere. Additional fuel vapors may be escaping depending on the cause of the problem.

Excessive Gasoline Smells

The escaping fuel vapors will give off a smell. This doesn’t narrow down the problem much as they could come from anywhere, but can point to a P0444 trouble code. If the EVAP system has failed, these smells would come from whichever side the system runs on. In most cases, this would be the driver’s side. That being said, make sure to inspect fuel lines, fuel tank, and other fuel-related components if you smell fuel in or around your car. 

Poor Starting behavior

Issues with your vehicle starting such as stalls extended cranking or idle issues are often caused by vacuum failure. It’s not always the case, but this behavior can cause the P0444 code, especially if the solenoid is leaking.

How to Diagnose and Fix the Cause of P0444 Code 

In an ideal world, we would have a device that tells us exactly where the problem is. Modern vehicles are complicated, so we need a detailed method to find and fix issues. Here’s how you can approach diagnosing this particular code. 

OBD-II Reader

An OBD-II reader is a must-have tool these days. It allows you to interact with the engine computer and detect any issues that have been logged. Today, they are accessible and cheap at any auto-parts store, so don’t hesitate to pick one up.

Plug the scan tool into the connection port under the passenger side dash. Scanning for trouble codes should give you the P0444 code. Look for any other related codes that might help you diagnose the problem as well.

Visually Inspect the Vehicle

First, you need to check whether the fuel cap is on. If the seal is damaged, or it is not on correctly, fuel vapors can escape from the fuel tank and cause this trouble. These vapors can also leak out of the fuel tank, so be sure to check for any holes.

Now, you need to inspect your solenoid. The purge control solenoid is usually located in the engine bay and easily accessible by hand. Check your owner’s manual for the exact location, it might also be called the purge control valve.

If there is any major damage like cracks, melting, or exposed bits, it needs to be replaced. Debris can also clog up the valve, so do not rule out that this is the root cause of your P0444 code just yet.

Next, check your wiring harness for damage. Frayed, exposed, or loose wiring can cause the signal voltage to be lost and the trouble code.

Vacuum leaks are a major source of issues. Now, maybe the failed solenoid itself is causing a vacuum leak, but a vacuum leak somewhere else can also cause the P0444 code. Check that the hose leading from the solenoid to the intake manifold is not loose.

These tests do not rule out internal damage but can save you a lot of time if there are visible signs of external damage.

Purge Control Solenoid

To check the purge control solenoid, you will need a vacuum tester, clamp, and small hose. There’s no real way to test whether there is a vacuum leak from the valve if it is still connected to the system, so we have to disconnect it and test it separately.

First, you need to test whether the valve is opening and closing properly. For this, we need to power the solenoid with a battery. Connect the negative terminal to the negative pin on your solenoid. Conduct the same process with the positive battery terminal. Once connected, you should hear an audible click coming from the solenoid.

We will now test that the solenoid is not leaking air. Connect your vacuum tester to the hose, and then the other end of the hose to the solenoid. Ensure that it is clamped properly as a hose leak will give you a false positive.

Pump around 15HG into the solenoid and watch the pressure for around 15 minutes. The pressure should not fall at all if the valve is functioning properly. If you add power to the valve, the pressure should drop to 0HG.

Wiring Harness Test

Here, we will test the solenoid for resistance using a multimeter. Set the multimeter to ohms. Contact the red probe to the positive solenoid terminal and the black probe to the negative terminal. A functioning valve should read between 14 and 30 ohms.

How to Fix a P0444?

Often your purge control valve can become clogged with carbon or debris and cause this trouble code. The easiest way to fix that is by using a carbon or MAF cleaner and a small toothbrush on the solenoid. A fuel system flush is also a good bet to resolve this trouble code.

Does P0444 Clear Itself?

This depends on the root cause of the issue. If your issue is a failed solenoid, the code should clear itself after a drive cycle is completed. Vacuum issues can be more tedious to clear and may require you to clear the codes with an OBD-II reader multiple times.

Is It OK to Drive with P0444?

Vacuum issues will cause changes in the air-fuel mixture and can cause serious long-term problems. Although you can drive with EVAP issues, you should fix the root cause as soon as possible.

Fix the P0444 Code Using Quality Parts! 

Diagnosing the P0444 code is only half the battle. Of course, you want to get back on the road as soon as possible, and that means that the failed parts need to be fixed or replaced. This needs to happen now!

Luckily, eEuroparts.com has all the parts that you might need for this trouble code and more. Select your vehicle from the dropdown menu, and you’ll see a list of parts that are a guaranteed fit for your vehicle.