Pontiac G8 Forum banner

Code P0455 (But not the gas cap?)

15K views 26 replies 13 participants last post by  Poppanitrous 
#1 ·
Hey guys I have had this code for a while now. I kept putting off doing anything about it since I thought is just just a bad gas cap. Well a couple weeks ago I finally grabbed a new cap off of amazon and thought that would be the end of it. Nope. I am still getting the same code with the brand new cap.

My question is what else is there that causes this code. I guess there is always that chance that the new cap is bad but I kind of doubt it. Any ideas?
 
#3 ·
Oh yeah I have cleared it a couple times. Keeps coming back. Cleared it this morning after checking just to make sure it was still P0455. I'll check how long it takes to come back this time. Usually it's only 1-2 days.
 
#5 ·
Common Problems That Trigger the P0455 Code

Missing fuel cap
Defective or damaged fuel cap
Distorted or damaged Fuel Tank Filler Neck
Torn or punctured Evaporative system hose(s)
Defective Fuel Tank Sending Unit gasket or seal
Split or damaged Carbon Canister
Defective Evaporative Vent Valve and/or Evaporative Purge Valve
Defective or damaged fuel tank
Defective Fuel Tank Pressure Sensor

I haven't gotten that code in over a year since I started tightening the gas cap with force behind it. I used to get it all the time when I purchased the car.
 
  • Like
Reactions: IsthataGT
#7 ·
my money is on the evap canister.
 
  • Like
Reactions: IsthataGT
#8 ·
They do say, that IF the purge valve, the pipe going back to the canister, the canister itself, or the vent valve (at the canister) has developed any blockage, or any leak, it could/would prevent the EVAP system from reaching the vacuum level it *must* attain within a prescribed time, or you will get that P0455 code.
I've never heard of any blockage from the piping, but there have been a few plugged canister/vent valve problems. Since there are no codes for the purge and vent valves logged in, seems like they must be cycling correctly (when commanded). Sure hope you don't have to mess with the canister and vent valve. But that combo has shown to be a fix a lot of the time (for a few different codes). If you are able to eliminate the gas cap and the possibility of a damaged gas fill pipe sealing surface (that the cap seals against) as a source, you may *have* to go there.
 
#25 ·
They do say, that IF the purge valve, the pipe going back to the canister, the canister itself, or the vent valve (at the canister) has developed any blockage, or any leak, it could/would prevent the EVAP system from reaching the vacuum level it must attain within a prescribed time, or you will get that P0455 code.
I've never heard of any blockage from the piping, but there have been a few plugged canister/vent valve problems. Since there are no codes for the purge and vent valves logged in, seems like they must be cycling correctly (when commanded). Sure hope you don't have to mess with the canister and vent valve. But that combo has shown to be a fix a lot of the time (for a few different codes). If you are able to eliminate the gas cap and the possibility of a damaged gas fill pipe sealing surface (that the cap seals against) as a source, you may have to go there.
Where can I find pics of location of canister and how to fix?
I just got code p0455 and erased it came back in 2days.
My car only has 36k miles
 
#10 ·
Look out! I was up against my NY state inspection running out and had to pay the dealer $800 to do the canister and valve. Yeah although I failed the inspection on emission equipment, it is not covered under the the emission system (go figure).

There are forums that get into doing it yourself. Kind of tricky to get at since they are high up by the gas tank but doable. I was out of time so had to pay the dealer.
 
#11 ·
#12 ·
I faced similar issues with $1000 bills and Evap crap. The thread was called Evap System & Unicorns.

I had my Evap system set to monitor but do not report using EFI Live. Not a single issue since.



Sent from AutoGuide.com Free App
 
#14 ·
#16 ·
I had the same problem, its the Evap canister that sits right above the fuel tank. You can easily see it through the rear passengers side wheel well. You will have to remove the tire to get to it.
I replaced it myself but I needed the help of my skinny girlfriend arms to reach it. Taking it off is a real pain in the ass. putting it back is easy if you have some kind of long vice grips that hold the clamp down while you squeeze the canister back in. If you have big forearms forget it. I never put the canister back on its brackets because that would had been nearly impossible, so its just sitting there, the hoses are thick enough that will not let the canister move/jump around easily.
 
  • Like
Reactions: IsthataGT
#19 ·
Yeti had a bit more trouble with it but he also had a different code. When I replace the purge valve under the hood I slightly damage one of the connectors on one of the lines that connect to it. I am guessing that may be my problem. Ill try to use a little silicone on it. If that doesn't work I think I'll just have the code tuned out. It just isn't worth messing with for me.

http://www.g8board.com/forums/showthread.php?t=136346



Also the code came back today. Took about 25 miles and 40 minutes worth of driving total for it to come back.
 
  • Like
Reactions: IsthataGT
#21 ·
Yeti had a bit more trouble with it but he also had a different code. When I replace the purge valve under the hood I slightly damage one of the connectors on one of the lines that connect to it. I am guessing that may be my problem. Ill try to use a little silicone on it. If that doesn't work I think I'll just have the code tuned out. It just isn't worth messing with for me.

http://www.g8board.com/forums/showthread.php?t=136346



Also the code came back today. Took about 25 miles and 40 minutes worth of driving total for it to come back.
When the codes come back that fast, that definitely says there is a problem and of course you know this. At least you know where you went wrong and possibly that being the problem. That would drive me crazy so personally, I would just try to replace the defective part.
 
#23 ·
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top