The P0442 Code on Chevy Silverado: Meaning, Causes, and Fixes

It starts with a check engine light and ends up being the most common code that Chevy Silverado and other GMCs display. Yes, I am talking about the P0442 code.

The code P0442 on a Chevy Silverado expresses an Evaporative Emission System (EVAP) Leak. Mostly a small leak is detected by this code. The vacuum in the EVAP system decays at a very fast rate.

However, you have no reason to worry because in this article I will discuss any questions you have about this code. Regarding why it occurs, and how to fix it. I will also discuss why the EVAP system is important and how it works

What Does P0442 Code Mean On Chevy Silverado?

The p0442 code in the Chevrolet Silverado indicates that an EVAP system leak has been detected. This is one of the most common fault codes, and it is usually caused by a loose or damaged fuel cap.

The powertrain control module (PCM) checks the entire EVAP control system for the presence of a small fuel vapor leak. When the EVAP running loss monitor test detects a fuel vapor leak from an opening as small as 1.016 mm (0.040 in), the system fails.

The PCM monitors the Fuel Tank Pressure sensor to determine the vacuum/pressure level in the EVAP system. When the Conditions for Running the DTC are met, the PCM turns on both the EVAP Purge Solenoid and the EVAP Vent Valve to apply an engine vacuum to the EVAP system.

Once the system has reached a predetermined level of vacuum, the PCM instructs the EVAP Purge Solenoid to turn off. The vacuum in the sealed system should HOLD the EVAP system.

This DTC is set by the PCM to indicate a minor leak if the EVAP system fails to maintain a predetermined level of vacuum for a predetermined amount of time. This DTC appears after failing the preceding test twice.

And now, let’s look at what the different parts of the code P0442 signify:

• P- Powertrain, the assembly of parts that move your car forward.
• 0 – Standardized code.
• 4 – Exhaust Monitoring System.
• 40 – Specific problem based on manufacturer. In this case the EVAP system small leak.

What Happens When the Code P0442 On Chevy Silverado Appears?

You will find small leaks, excess vacuum and purge flow during non-commanded conditions. Additionally, the fuel level and fuel pressure sensor faults are found. The EVAP purge and vent valve faults are common.

Other problems with the truck could include a faulty vapor canister purge valve, a fuel vapor hose leak, or a damaged fuel tank pressure sensor.

You will also find the codes P0446 and P0440 too along with this one. With multiple codes, you may lose your fuel gauge fuel pump.

It may also take an eternity to fill up the gas tank. You may also notice a strong fuel odor that is most noticeable down by the rocker on the driver’s side.

What Causes Code P0442 On Chevy Silverado?

Here are a few reasons why the code P0442 sets on a Chevy Silverado:

• Leaks of all sizes.
• A lot of vacuum. The EVAP system’s vacuum degrades (leaks) far too quickly.
• Purge flow when no commands are given.
• Fuel Pressure Level Sensor Issues.
• Faults in the EVAP Purge and Vent Valve.
• On the second consecutive ignition cycle after the diagnostic runs and fails, the PCM turns on the malfunction indicator lamp (MIL).
• An incorrectly installed or loose gas cap.
• A gas cap that is not factory- or original-brand compliant.
• A tiny crack or hole in a fuel vapor tube or hose.
• Vent o-ring seal issue.
• Vacuum and vapor lines in an EVAP system that are misrouted or broken.
• A broken or dysfunctional vapor canister. Inspect for charcoal release from the vapor canister.
• Another sensor on the intake manifold could be related to this issue as well.
• The slow fill problem is from a blocked EVAP vent path.

How To Fix The P0442 Code On The Chevy Silverado?

Step 1

Always start with the purge valve. The Chevys have finnicky purge valves. They always go out. Testing is simple and quick.

Use a vacuum hand pump and simply connect it to the purge. Vacuum is on the gray side. It won’t need to hold when sucking in the opposite direction because it will hold on the gray side.

Disconnect the EVAP hose that leads to the gas tank and connect the glein to it. Then pump it to see if your previous pressure holds. We’re good to go if it holds. If not, we’ll need a purge valve.

A loose gas cap is the most common cause of an EVAP code. Check that the gas cap is completely tightened and that the seal around it is not damaged.

There is another way to do purge test. With the engine running, unplug the electrical connection and the vapor line to the purge valve and check for any vacuum at the purge line connection.

If there is any vacuum while the engine is running, change it. Running the engine with the purge valve unplugged will most likely result in a P0443 code.

An AC Delco purge valve is your best bet on Chevys!

Step 2

A smoke test on the system is the quickest way to find the leak. Otherwise, you might have to replace a lot of parts before you find the source of the leak.

The most typical fix involves taking off and replacing the gas cap, clearing the codes, and driving for a day to see if the codes return.

The “TIGHTEN FUEL CAP” warning was programmed into the DIC because, in these days of self-service gas, that is the most typical cause of an air leak in the EVAP system.

The leak may not be coming from the fill cap. Take it in for service if a visual inspection or smell doesn’t reveal anything. Replace the gas cap or check the EVAP system for any hose or tube damage.

Use acetone or alcohol to clean the neck’s lip before replacing the cap. There is occasionally a buildup of dirt. Even something as small as a grain of sand is enough for the vapor purge sensor to think there is a system leak.

Step 3

There may be an EVAP Solenoid issue. Change the solenoid under the truck. If the old one is defective, replace it.

You can test the old one by touching the connection on the solenoid with a 9-volt battery, positive and negative. When touched, you should hear a click.

Clean the seals, remove any debris from the canister, and then reassemble it. Vent solenoid is a good candidate. The dealer will charge a lot to replace this part.

Over time, the filter clogs, and the vent solenoid signals the computer to set a code. Along with an electrical connection, it will have a substantial plastic line running from the EVAP canister to the solenoid. The solenoid and a remote filter are part of an updated kit that you mount on top of the transmission.

Step 4

If nothing else works (after changing the purge valve, vent valve and solenoid), here’s what you can do:

• Change the fuel pressure level sensors.
• Change the fuel vapor tube or hoses.
• Ensure that the vent o-ring seal is tight and has no leak. Seal the leak if you find any or change the damaged o-ring.
• Replace broken or dysfunctional vapor canisters.
• Change any failed sensor on the intake manifold. Check if it has voltage. If it doesn’t, it’s time to change it.

How Much Does It Cost To Fix The Chevy Silverado P0442 Code?

If you can’t find leaks but the code won’t go away, change out the tank. However, that may cost you around $1100. This is a financial nightmare.

The price range for the solenoid and pump kit maybe $85 and up. Gas caps are cheap, ranging between $20-40.

Can You Drive Your Chevy Silverado With Code P0442?

Yes, you can. As long as you’re driving a few miles, there is no need for immediate concern about its short-term drivability. However, the fuel leak is an issue and should not be taken lightly.

Get the problem fixed as soon as you can.

Frequently Asked Questions (FAQs)

Conclusion

With the code P0442 on a Chevy Silverado, it often feels like you are on a wild goose chase trying to solve this problem.

But from this article you know, it is really not that difficult. The problem is pretty easy to solve if you follow my instructions.

I hope you got some great ideas on how to fix this problem from this article. Get that Silverado back on the road. Cheers!