Minor Evap. Leak Code P0440

SavageUrge · **Posted:** Sun Jan 27, 2008 5:21 pm

This is what I found so far, but I could use some more help:

Evaporative Emission Control System Malfunction (My code scanner actually says "(Minor Leak)" at the end of the definition, rather than "Malfunction")

What does that mean?This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

SymptomsYou likely won't notice any drivability problems.

CausesA code P0440 could mean one or more of the following has happened:

The gas cap is not installed or working properly
The purge solenoid has failed
The canister is plugged and not working properly
Possible SolutionsWith a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
Inspect the EVAP system for cuts/holes in tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks
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I tried the gas cap trick and the light came back on the next time I started the Jeep. Where can I find the Evap system parts, so I'll know where to look next? THANKS EVERYBODY!!

Wahoo650 · **Posted:** Mon Jan 28, 2008 7:16 am

Haven't had P0440... yet but have had P0441 and now P0442. The rubber hoses used to join all of the semi-rigid lines in the evap system are junk. dry rot and crack at 3-4 years. I found that all of the pcs back at the canister needed replacing to clear P0441, which is the same basic description as P0440 (small evap leak). Just start at the intake and follow the lines back, replace any and all rubber. It's 5/16 ID for most of it. Go buy 3 ft. of emissions/fuel line at your local auto parts store and have at it. Don't forget to clear codes by disconnecting the negative terminal only. I'm waiting for warmer weather to get back under mine for P0442.

Prospect62 · **Posted:** Mon Jan 28, 2008 10:45 am

Yeah, I got a P0455 and it ended up being a rubber hose crack issue. All the way in the back above the rear axle there's a black box with rubber hoses going into it. That's the EVAP canister. Check the rubber hoses going into it for cracks or loose connections. Then look under your hood for cracked or rotted rubber hoses (right next to your battery there is a line with a green cap on it, those are the lines you should check, also the hoses going to the air intake, etc). Chances are, you'll find a cracked or broken hose and that's your culprit.

Good luck.

SavageUrge · **Posted:** Mon Jan 28, 2008 6:04 pm

Thanks, good info!

yakers · **Posted:** Mon Jan 28, 2008 7:46 pm

Had this code interemittently on my XJ. Had it to the dealer on a different service and they could not find anything wrong with my evap system. So I have a code reader and periodically check to see that there is no other code coming up and just ignore it. But sometimes it does not come up for a week or two. I just clear it before smog check and it passes.

SavageUrge · **Posted:** Mon Jan 28, 2008 7:48 pm

I tried clearing it, but it comes back on the next time I start the Jeep.

Minor Evap. Leak Code P0440

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