OBD2 Code P0440: What It Means

Figuring out why your Check Engine Light is on means deciphering OBD-II (or “OBD2”) codes, and that can be kind … Continued

Figuring out why your Check Engine Light is on means deciphering OBD-II (or “OBD2”) codes, and that can be kind of annoying. That’s why Car Bibles did it for you! You’re welcome, now let’s get into solving your issue.

OBD2 P0440: What It Means

This code reads as EVAP control system malfunction.” This means that the engine computer (typically) reads a lower-than-usual pressure in the EVAP system, usually signaling a leak.

Likely Symptoms 

Here’s what you may experience due to the P0440 code:

  • Check Engine Light. Almost guaranteed, as the engine computer self tests regularly.
  • Fuel smell (rare). If the leak is bad enough, you may get a fuel smell, though it’s very rare.

Probable Causes

Here’s what could be causing the issue:

  • Loose/bad gas cap. Your gas cap could simply be loose, and need a few more clicks to tighten it. If not, make sure the cap seals and the rubber in the cap isn’t dry. If it is, it could need a replacement
  • Leak in EVAP system, charcoal canister, fuel filler neck, or vent valve. The code only states a general malfunction in the EVAP system, so make sure to check all the big stuff around your gas tank.

What Part Is Potentially Affected?

It could be a faulty gas cap, or anything in the EVAP system causing a leak. Most of the time, it will be the gas cap, so there isn’t much to worry about. This code generally shouldn’t hurt the car in any significant way.

Possible Fixes

Here are the most common fixes to remedy the P0440 code:

  • Tighten the gas cap. Make sure the gas cap is tight, and see if the check engine light goes away after a few miles.
  • Replace the gas cap. If the rubber in the gas cap feels dry or brittle, it likely needs replacement. Any auto parts store will have it, and they’re inexpensive.
  • Smoke test the EVAP system. Cheap smoke testers are easy to get these days, get a smoke tester and smoke test the car, usually through the gas cap with some rags. The smoke will leak out of the affected area, and you’ll know what to replace.

Finding The Parts You Need

Now that you’ve figured out what’s wrong with your hooptie, let’s talk about where you’re gonna find that part’s replacement.

There are plenty of places you can buy auto parts from, but Car Bibles gets paid if you click this Advance Auto link so that’s the one we’re serving up. Advance Auto Parts also has delivery, curbside pickup, and a host of helpful diagrams to aid your repair!

Chris Rosales
Chris Rosales

Chris has owned 12 cars of questionable quality, is an experienced motorsports photographer, and a good all-around wrench. When he isn’t tinkering with his car in his home garage, you can catch Chris in the canyons around SoCal. He also hopelessly hankers for Euros, but he honestly knows he should get something Japanese, eventually. Contact the author here.