Since 1996, all manufactured cars have had an OBD error code system. The car’s computer gathers information from different sensors, thus checking how the car is working. While most OBD-II error codes are followed by some symptoms, the P0442 code doesn’t. The only thing that you will notice is an illuminated check engine light.
The P0442 code indicates that there is a small leak in the evaporative emission control system (EVAP). The purpose of an EVAP system is to keep the gas vapors from ending up in the atmosphere. The engine control unit (ECU) is conducting an EVAP test to see if is it working properly. During the test, the ECM is checking the system for leaks. If there is a leak, then it will signal a P0442 fault code.
Several OBD-II error codes are focused on EVAP system leaks. EVAP faults include the P0440 and codes between P0443 and P0449. The P0442 is the infamous one because locating a small leak is a tough job. Stay with us, while we dive into this problem and ways to resolve it.
Understanding the P0442 OBD2 Code
The EVAP system codes are not that common. Most drivers are not accustomed to the EVAP system and don’t know its purpose. That is why we decided to cover this topic altogether.
What Exactly is the P0442 Code?
The simple explanation of the P0442 code is that there is an EVAP system leak. While conducting an EVAP test, the ECU checks if is there a leak while the engine is not running. If it detects a small leak, it will release a P0442 code.
Technical Interpretations of the P0442 Code
While the number of new cars varies from year to year, it is unquestionable that we are using them now more than ever. While the engines are burning fuel, they are releasing different harmful emissions into the air. That is why the manufacturers are installing several systems to keep vehicle emissions low.
One of the systems that is responsible for lowering emissions is the EVAP system. The vent lines from the fuel tank are directed to the EVAP store canister. There the fuel vapors are stored in charcoal pellets.
When the engine is warm and running, the ECM will open the vent control valve. That directs fuel vapors into the EVAP canister. The ECM will, from time to time, command the purge valve to burn the vapors. To do so the fuel vapors are transfered into the intake manifold. From there, the vapors are burned in the engine.
When the engine is turned off, the ECM conducts the EVAP system leak test. During the test, both the vent control valve and the purge valve are closed off. The EVAP system is sealed tight, allowing the ECM to check for leaks.
If the EVAP system cannot contain the pressure, then the ECM detects the leak. Depending on the pressure change the scan tool will put out a different code. If the leak is small, it will show a P0442 code.
The Role of the EVAP System in the P0442 Code
The EVAP system needs to prevent the escape of fuel vapors. Fuel fumes can escape even when the engine is not working. While the engine is working, the EVAP system helps to burn off any excess fuel vapors.
If there is a leak of any kind, that can cause lower fuel efficiency, and your car may not pass the emission test.
Causes and Symptoms of the P0442 Code
The P0442 code indicates that there is a leak in the fuel system. That leak can cause the vapor to leave the vehicle and end up in the atmosphere. The cause for the leak can be a small issue, like a loose fuel cap. But, it also can point to a problem with a fuel tank that is leaking.
Most Common Causes Behind the P0442 Code
- Gas cap issue. The cause for a P0442 code can be a simple error like a loosely tightened gas cap. Also, it is worth doing a fuel cap inspection to check if is it holding the fuel fumes. A cracked gas cap seal will also cause this issue
- Charcoal canister leak. We mentioned that the vapors are stored in the charcoal canister. If it is leaking it will cause a P0442 code
- Faulty purge control valve. When the time comes to purge the fumes, the purge valve needs to transfer the fumes to the engine. If it is not working properly it will trigger the code
- Faulty vent control valve. The vent control valve moves the vapor into the charcoal canister. If there is a problem with it, that will also result in a P0442 code
- Leaking or disconnected EVAP hose. The EVAP hose is an essential part of the EVAP system. If it is leaking or disconnected it will trigger a P0442 trouble code
- Fuel tank leaks. If the tank is leaking that means that the vapors are moving freely. That should not happen and will trigger a P0442 EVAP code.
Check Out P0442 Where Leaks Happen & Easy Common Fixes:
Identifiable Symptoms of the P0442 Code
It can be hard to detect any symptom of the P0442 code. A small leak doesn’t doesn’t cause a large fuel vapor leak, or other major mishaps. The only sure thing is a glowing check engine light. But, there are some things that you can notice if you pay attention to.
- Increased fuel consumption
- Check engine light is on
- Fuel smell
- Failed emission test
The Mechanics Behind the P0442 Code
The sole purpose of the EVAP system is to not allow fuel fumes to leave the car. That may sound trivial, but without it, the fumes would be constantly leaving the car. That is dangerous both for the driver and for the environment.
How Your Car’s Computer Detects the P0442 Code
When the vehicle is not running the ECM is conducting an EVAP leak test. The ECM seals off the evaporation system by closing off the vent control and purge valves. If the pressure inside the system falls, that points to a leak.
What Happens Inside Your Vehicle When the P0442 Code is Present
The EVAP system is there to seal the vehicle to avoid releasing fuel fumes into the atmosphere. When there is a leak in the system, that means that the fumes are released into the air causing additional pollution.
Troubleshooting the P0442 Code
In most situations, drivers won’t notice any obvious symptoms, like performance issues. The engine will not stall or have problems at idle. That is why it can be difficult to notice a problem with the EVAP system. Fuel economy may drop a bit, and you may notice a fuel odor.
The diagnostic process for the P0442 code is not an easy task to do at home. If you have some mechanical experience, you can try to do it yourself and save some money. If you are not into DIY mechanics, contact a mechanic.
Step-by-Step Guide to Diagnosing the P0442 Code
- Connect the vehicle to the OBD-II scanner. Check if there are any other OBD2 error codes. Other EVAP system codes are P0440 and between P0443 and P0449. These can point to a problem with an EVAP solenoid or a charcoal canister
- Inspect the fuel cap. This is a common issue and drivers sometimes cannot even detect damage on the fuel cap. If you want to eliminate this as an issue, replace the cap either way
- Check the EVAP hoses going to the airbox. If they are damaged or disconnected, fix or replace them
- Do a visual check of the fuel tank. There can be problems with dents, corrosion, or other damage. Assess if the tank is repairable or if it should be replaced
- Check the charcoal canister. If it is damaged or leaking, replace it
- Examine the purge volume control valve. When it is not powered the air won’t pass through it. But, in some cases, the valve can stick, leading to leaks. Blow the air through it when there is no power. The air should pass through. Now repeat the test with power. The air should not pass. If you detect any problems, replace the valve
- Check the charcoal canister vent control valve. Remove the hoses from both sides of the valve while the engine is off. Remove it from the car and disconnect it from any power source. Blow through the openings, and the air should pass through. Now, connect one side to the power source, and the other to the ground. Blow the air again. If the air is not passing through, that means that the valve is closed and working
- Do a solenoid test. Set the multimeter to measure resistance (ohms). Contact the solenoid terminal with both red and black probes. If the solenoid is working properly the multimeter should show between 14 and 30 ohms
- Do a smoke test. You can buy a smoke machine leak detector to check for leaks in the system. Close off the purge valve solenoid and the gas cap. Attach the machine to the car’s battery, and turn it on. Close the vent solenoid. Grab a flashlight and check for any leaks in the system. This test can be also done by a mechanic, so you do not waste money on a smoke machine.
Essential Tools to Fix the P0442 Code
Besides some basic mechanic hand tools, you will only need a smoke machine leak detector. If you want, you can use a multimeter to test the purge control valve and the solenoid.
Preventing the P0442 Code
The EVAP system is not prone to problems. It can last for years without a glitch. But, in some cases, the problem may arise. We have a couple of advice to prevent this error from happening in the first place.
Maintenance Tips to Avoid the P0442 Code
The most obvious problem that can cause this error is the leak on EVAP lines or hoses. Sometimes, disconnected EVAP lines or hoses will cause this issue. Be sure to tell the mechanic to do a visual inspection from time to time.
The next in line is fuel tank leakage. The problem can be in the corrosion or if the tank is old and worn. If you notice any leaks under the vehicle, tell the mechanic to do a check.
Regularly inspect and change the O-rings on the lines and hoses. They are preventing fuel leaks by keeping the fuel lines and other components secured. They will become worn in time, and they can crack.
Upgrades and Replacements to Keep the P0442 Code at Bay
- Secure the EVAP hose with zip lines to prevent it from falling off
- Buy an upgraded fuel cap.
FAQs about the P0442 Code
Can You Still Drive Safely With A P0442 Code?
No, you cannot safely drive with a P0442 code. Fuel vapors are highly flammable, and under specific conditions, they can be ignited. Some mechanics say that the P0442 code is not dangerous, but because the fuel is in question, we recommend resolving this issue as fast as possible.
Is an EVAP Leak Serious?
An EVAP leak can be a serious issue. It depends on the underlying cause of a leak. That is why proper diagnosis is very important.
What Is the Most Common Cause of an Engine Code P0442?
The most common cause of an engine code P0442 is a loose fuel cap. Also, a disconnected EVAP hose is a frequent cause of the P0442.
How Much Is the Cost to Fix P0442?
The cost to fix a P0442 depends on the problem that is causing it. Here are the costs for the usual suspects for this error:
– Gas cap replacement: $20-$60
– Purge Volume Control Valve: $150-$200
– New EVAP Line: $50-$100
– Charcoal Canister: $200-$600
– Charcoal Canister Vent Control Valve: $150-$200.
On these costs, you need to add the price of labor, which can vary between $75 and $150.
Need More Help with a P0442 Code?
A P0442 code is an error that can be hard to diagnose. The smaller leak is harder to detect than the large one. That is why diagnosing and fixing errors should be left to the professional. It is important to mention that an EVAP leak can be dangerous. Fuel fumes are highly flammable, and we advise every driver to resolve this issue as soon as possible.
