P0455 Code

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Oct 13, 2003 | 12:21 PM

florit

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P0455 Code

My check engine light has been going on and off intermittantly now for a couple of years. Took it to Ford a couple of times and each time they replace something different but the light keeps coming back on eventually. I went to AZ because I got tired of dishing money out to Ford without the problem getting resolved. When the guy at AZ hooked up, a code of "P0455" came out with a message saying 'emissions leak (large)". I looked all around my exhaust system and found that where the clamp holds the pipe going into my muffler had shifted, and there was exhaust coming out there. I say that because you could see where the soot had built up shooting out from the bad connection. I've just fixed the conection by loosening, then repositioning and retightening the clamp. Now I'm waiting to see if the light will reset itself. After all this, my question is would that cause the code I'm getting or did I just fix something else that needed fixed and I still have a problem?

Oct 13, 2003 | 12:41 PM

florit

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I forgot to mention, it's a 97 F150 supercab.

Oct 13, 2003 | 04:28 PM

Racerguy

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Hi florit and welcome aboard

A P0455 is for the Evaporative Emissions system. The system has detected a large leak or no purge flow.
It could be something as simple as a gas cap that isnt sealed properly but in my experience it is quite often a problem with the canister purge valve or solenoid or the wiring to them.
The canister purge system is at the back of the truck, above and behind the rear axle. There is one wiring harness going to it. I've seen those corroded and torn off. The wiring harness connects to the canister purge valve which can also malfunction. Mud in them also can cause the code. If the wiring looks ok I think I'd pull the purge valve out and see if it's plugged up.

Oct 18, 2003 | 03:16 PM

florit

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Thanks for the feedback Racerguy. I checked the wiring harness, it looks to be in good shape so I pulled the canister assembly, wasn't that bad to do, and I took apart the whole thing. Besides being dirty on the outside everything inside looked clean, dusty perhaps but no mud or any major dirt or clogs that I could tell. Any thing else I should look for???? OH, say I fix whatever is causing the problem when will the light go out??? I understand I have to drive 3 "drive cycles". What defines a drive cycle for my vehicle?? Thanks for the help.

Oct 18, 2003 | 08:41 PM

Racerguy

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Probably the next thing to do would be to check the resistance of the CV solenoid. It should be 48-65 ohms. If not you should replace it. If that isnt the problem you might have an EVAP leak which will probably have to be checked a shop with a smoke machine. With a proper scan tool the tech can open and close the different solenoids etc while filling the system wtih smoke and then checking to see if the smoke leaks out anywhere.

Once the problem is fixed you can just pull a battery terminal off for 10 minutes or so which will clear the code and turn the light off. An OBD2 drive cycle consists of some highway driving, some slower driving, medium accelerations, idling etc. Normally a few days of normal driving will complete a cycle. During the drive cycle the truck's PCM looks at all the different sensors etc and either passes or fails them.

Oct 20, 2003 | 07:14 AM

florit

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I have a digital multimeter at work, I'll be checking that today. If I pull the battery terminal to clear the code and the problem still exists will the light come back on immediately? If the light doesn't come back on how long do I have to wait to be able to get it inspected?

Oct 20, 2003 | 08:56 PM

Racerguy

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Any luck with it?
When you ask about having it inspected are you talking about emissions testing?
If you are talking about that, you will have to do a complete drive cycle with no problems before it will pass testing. After clearing codes the PCM will have a P1000 code in it which means that all the "monitor" tests are incomplete and further driving (hopefully) or repairs is neccesary.