Hello All, Got a CEL the other day, had the code pulled (PO455)
Evaporative Emmisions System Leak- Gross. I replaced the gas cap and reset the computer but the CEL came back. Can someone give me some suggestions on where to start looking.
Thanks in advance.

 

Attached below is the actual section from the service manual.

First some inital questions / thoughts / pontifications :

This is not only a large leak, but also a no purge flow error ( you only got half the description ). So while the system might be completly closed, it could be a bad solenoid or valve that did not close on the canister.

1. Have you done anything in the engine compartment in the past 2 weeks or so. Asking as if maybe you knocked a line loose, and it just gave up the ghost and finally fell off. In perticular around the back of the battery.

2. Have you had alot of wet weather driving, or driving in dusty conditions ? Maybe the door is crapped up, and needs to be cleaned / replaced on the canister ( don't know for sure if it is a seperate part or not ).

3. Do you get the noted heavy fuel odors ?

Just a few items of note, in the problem diagnoses area.

Let us know what you come up with, I am sure JMC will be along real soon with some more pointers, on stuff I forgot to ask, which I am sure there are some.

DTC
P0455 - EVAP Control System Leak Detected (No Purge Flow or Large Leak)

Description
The PCM monitors the complete EVAP control system for no purge flow, the presence of a large fuel vapor leak or multiple small fuel vapor leaks. The system failure occurs when no purge flow (attributed to fuel vapor blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running (but not at idle).

Possible Causes
After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube
EVAP canister purge valve stuck closed
Damaged EVAP canister
Damaged or missing fuel filler cap
Insufficient fuel filler cap installation
Loose fuel vapor hose/tube connections to EVAP system components
Blockages or restrictions in fuel vapor hoses /tubes (items also listed under disconnections or cracks)
Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked
Canister vent (CV) solenoid stuck open Mechanically inoperative fuel tank pressure (FTP) sensor

Diagnostic Aides
Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank.

 

WOW, Thank you for the quick and indepth response.I did some snooping around tonight. I could not find any obvious vacuum leaks, I do notice a what seems to be a more than normal exhaust smell but could find no leaks. I assumming the charcol canister is the oblong box at the rear above the spare tire. I checked the hoses there as far up to the top of the tank that I could and could find no cracks. As far as recent events, I haven't been in any really wet conditions however tvice a day I have to drive on a very dusty road. The only thing I can think of was that I had hit a massive pot hole Saturday and the CEL came on Sunday ?

 

That could be the case, the jolt was the last one that the valve took, before giving up ?? Got me that is a big guess.

If I can, I'll try to look up the evap system diagrams, drop me an email in my profile, so I can send you the jpeg of it.

It might come in handy for tracing all the lines.

The other is the solenoid gave up, or the control to the solenoid might have gone awry ?? These are just SWAGs at the moment.

I don't know if JMC is around tonight or not, he might / should have some better info then myself.

Drop me a line, and I'll try to be as quick as poss, in getting that back to you.

Good luck, keep us updated, and what the outcome is, all the other postings on P0455 have no resolution to them, at least posted online. Your post might help the next member with this problem.

 

The quickest & easiest way to find leaks in the Evap. system is to have a static test done. This is done by injecting smoke into the system to determine where the leak is. You can have this done at any Ford or L/M dealership. It could be in any of the areas that sscully mentioned. Good Luck!

 

Any idea how much this would cost?
I have codes P0455 and P0174 right now. Is it possible one of those codes tripped the other one also? I do know what each code is.
Thanks!

 

i just got a check engine light and my gas cap light had been on for a few months just never cared i was like it is the gas cap what ever its on there. Yesterday i got a check engine light and i took to the dealer today my purgevalve was clogged. now the gas cap light is off and the cel is off to. but i havent driven much just home from the dealer thats all. which is 15 minutes away

 

I have a diagram SSCULLY -



More diagrams and full explanations for your EVAP @ Scorpio . -

http://www.fordscorpio.co.uk/evapmonitor.htm

Also your PO174 is explained - Once your at the site , look to the column on the left, hit "fuel monitor"..

Also, on the 98 you should check the overflow tube that runs beside the main fill tube . They can come loose and move around enough to wear a hole in it towards the top. Mine did..

 

Who me?

 

Sure, I guess you added the PO174 - So I did too

I guess you and Lou are going thru the same problems just about, both 98's. The exception being that - your lean man , lean on bank 2 - not good.

Check for a vac leak as well , behind the TB .. Right here , that line with the 90 on it likes to leak and is a common problem for the PO174 code. Heres a pick of it -



Also A dirty MAF will throw that code ..

How to clean the MAF -

http://www.fordf150.net/howto/clean-...low-sensor.php

 

Lol, actually im trouble code free right now!! I did have a huge vacuum leak though and fixed that awhile back...

Caption: PCV hose elbow leak
Description: Elbow right underneath throtle body.


I cleaned my MAF awhile back too, first time ever I think.

Although I did floor it in first gear and my check engine light came on but I dont remember what the code was... I think it was "bank 2 too lean." I erased the code and my check engine light hasnt been on in almost 2 weeks.

I am bookmarking this thread though... just in case. Thanks!!!!

 

Yea, that's the sucker right there JT

Strange how they split like that, but it happens allot, even in the 4two ..

Great pick and comparison as well - I think I'll save that and give you the credit of course if I post it.

How much did they charge you for the elbow?

 

Heh, the 4two?

Knock yourself out with the pic. It'll be in my gallery forever probly along with all the others.

Lemme look up my "Truck" folder in my filing cabinet........ damn I have a lot of receipts from the dealer.....
Hmmm $12.08 for the elbow.
$108.53 for camshaft position sensor
$20.88 for a new gas cap
$106.86 for a new negative battery cable
$13.90 for some "Bracket" ???? F65Z17A385BA
$46.91 for new V-Belt
$16.17 for new hvac fan speed Resistor
$31.98 for new 4x4 sensor, (oil switch) ...in photo gallery

hahaha non dealer...
$216.03 for new Windshield installed during rain in crammed garage
$74,59 for Air Conditioning recharge
$100.92 for new Goodyear Wrangler RT/S P255/70/R16


Ok I definetly spend too much money on my truck.:o