P0440 code

signalnc

Original poster
Member
Dec 28, 2012
249
Hi all

I have a P0440 code on my 2003 trailblazer ext LT. I got a print out from the auto parts store that states possible fixes and it's a pretty long list. Can anyone tell me where I should start? Thanks.
 

TangoBravo

Member
Dec 5, 2011
208
If I remember right my p0440 was a bad gas cap. Altho to be honest I never actaully checked the code because I knew the cap was bad. I think when I noticed the p0440 it was stored.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Start with a new cap (aftermarket units are available) and hope it's not the cracked filler neck syndrome. Although you might be lucky and be included in the batch of vehicles that get assistance or a free fuel tank.

Added: The search word "P0440" DOES have some hits here with excellent advice, as does the archives back at trailvoy.
 

signalnc

Original poster
Member
Dec 28, 2012
249
thanks--I'll start with the gas cap. just curious when the filler neck cracks is it obvious to see? or is it more of a hairline crack?
 

signalnc

Original poster
Member
Dec 28, 2012
249
thanks. i got a new gas cap and cleared the code. I'll see what happens. thanks again.
 

TheGambler

Member
Sep 12, 2012
39
PO440 is evap malfunctions right. Well I don't get the free tank and I have the crack around the filler neck. I have replaced the filler neck. I was thinking of using JB Water weld for gas tanks what about the black box mounted on the side the that hooks to the tank ?
 

signalnc

Original poster
Member
Dec 28, 2012
249
I got a new gas cap, cleared the code and it came back on. I did look at the fill neck/line going to the gas tank. I do see a spot that is wet. It is right at a joint between two pieces. Looks like there is a rubber line going from the top, near the actual fill, then that connects to another piece in the middle that looks like it's either metal or hard plastic. Thats where the leak is. it's right at the frame. Where the two connect.

I was looking at replacement parts and it looks like i have to buy the whole part, not just the section that is leaking.

and one other thing. i replaced the fuel cap and can't get the holder ring on the new cap. is there a trick to get it on?
 

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