P0442 Code – Meaning, Symptoms, Causes (& How to Fix it)

A guide of how to diagnose & repair problems causing the P0442 trouble code

OBD2 trouble code

P0442 is a trouble code that appears in your engine control unit when it detects a leak in the EVAP Emission system.

There could be many different reasons for this. Here is everything you have to know about the P0442 code.

P0442 Definition

EVAP System Leak Detected (Small Leak)

What does the P0442 mean?

A P0442 code means that there is a leak in the EVAP emission system.

The EVAP emission system is a sealed fuel gas system, which is then going through your car engine because of environmental purposes. If the engine control unit recognizes a leak there, it will be stored as a P0442 code.

This code is very similar to the P0455 code, expect this code means that there is a small leak. The p0455 code means that there is a big leak.

P0442 Symptoms

You will most likely not experience any symptoms of a P0442 code other than the check engine light.

How serious is the P0442 Code?

Very Low – There is no danger for your engine to keep driving with the P0442 code.

The only thing that could happen in rare situations is that your engine might run slightly leaner than usual because of the leak. It is also bad for the environment.

Causes of the P0442 Code

The most common cause of a P0442 code is that you let your car engine run at the gas station with the fuel cap removed. It can also be a leaking fuel cap or a broken hose.

  • Defective bleed and vent control valves.
  • Damaged gas cap.
  • A leak in the charcoal canister leak.
  • Leaking EVAP hoses.
  • Leaks in the main fuel tanks.

What repairs can fix the P0442 code?

  • Tightening the gas cap & remove the trouble code.
  • Replace gas cap
  • Replace EVAP control valve
  • Replace EVAP hoses
  • Replacing charcoal canister
  • Replace Fuel tank

Common P0442 Diagnostic mistakes

The most common diagnostic mistake for the P0442 trouble code is to start a deep diagnostic. Usually, this trouble code appears when you didn’t shut off your car while refueling it at the gas station or a faulty gas cap. These are two super simple things you should check before starting diagnosing your car.

How to diagnose the P0442 Code

  1. Connect your OBD2 Scanner and check for related trouble codes. Make sure the trouble code is not stored by mistake after refueling.
  2. Make sure the gas cap is tightened, and the sealings look fine.
  3. Check the EVAP solenoid. Check the function by sending power to it. Make sure it is sealed when it’s closed. Check the wirings to it and make sure the engine control unit sends + and – to it.
  4. Remove the fuel vent line and pressurize it towards the tank. It should be sealed, and if you notice a leak, you can use an EVAP smoke machine to put smoke into it to find the leak easily.
  5. If everything is sealed and the solenoid works, you can now remove the trouble codes and test the car.

Related Trouble codes

Estimated P0442 Repair Cost

Here are some examples of the repair costs of the P0442 code. The prices include parts and labor. It does not include diagnosis costs.

  • Gas cap replacement cost – 20$ – 80$
  • EVAP control valve replacement cost – 40$ to 80$
  • Vacuum hose replacement cost – 10$ to 80$

Common P0442 Related Questions

How to fix P0442 code?

To fix the P0442 code, you most often just have to tighten or replace the gas gap. It can also help reset the P0442 code if it appeared after running the engine without the gas cap tightened.

What causes code P0442?

The P0442 code is most often caused by a not tightened or faulty gas cap. It is often also caused when you were refueling your car without shutting it off.

What does P0442 mean?

The P0442 means that the engine control unit recognized a leak in the EVAP system, which controls the gas tank’s fuel vapors.

How to clear code P0442?

To clear the P0442 code, you need to use an OBD2 scanner. Just connect the diagnostic scanner, clear the codes, and take your car for a test-drive.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.