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Cadillac CTS
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Discussion Starter #1
First post here. Pulled a PO496 from my daughters 03 CTS. It says Evap puprge when purge not called for. How about you tech guys, what do I check for?
 

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Check out my CTS here: http://www.fquick.com/FL01SS
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Welcome To The Party!:bouncy:

Sorry, I have no answer for you!:banghead:
 

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Check the gas cap and make sure it is on and clicks. Check to see if anyone filled up and left the car running. After that its going to take several starts and runs before the light goes off. If you don't use the car often it takes several long runs for the light to go out....more than just starting it and shutting it off.
 

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Cadillac CTS
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Discussion Starter #5
Well thats the first thing I had her do is replace the cap. I guess next is the hoses. I had her reset the light at her local Autozone. Any other ideas? Is there a purge valve and if so where is it located? Thanks for the quick response and being newto this board you guys are [email protected] I didn't realize how many perfomance guys are hot on these Caddy's. My daughters is a 5spd and seems to be a fun car to drive. I know at 22 she thinks it's the shit.... and so is she....
 

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Cadillac 3.6 CTS
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P0455 - Evaporative Emission (EVAP) System Leak Detected..... does this equate to my gas cap not on tight? i reset it and hopefully it doesn't comeback. my car is 07 3.6cts with 236 miles. warning signs?
 

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Cadillac Technician
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P0455 is usually a loose or leaking gas cap.

On CTS a P0496 is likely a leaking purge solenoid.
The EVAP system has a vent, the tank, tubing and a purge valve.
The vent equalizes pressure between the tank and the atmposphere.
The Engine controller closes the vent valve during certain tests. On the tank somewhere there is a wein bridge type sensor (sort of like a MAP sensor) that measures the pressure inside the tank.

The P0496 test closes the purge valve and the vent valve and then watches the pressure sensor (FTP or fuel tank pressure sensor).
If the FTP measures a decreasing pressure during this condition it is flagged as "flow during non-purge".
Some older systems actually have another sensor in the purge line to detect flow by monitoring pressure (the old P engine in the RWD Fleetwood and F car is a good example).

Basically what it is saying is that the purge valve is leaking, this allows engine vaccum to bleed into the line and decreases the pressure in the tank. In the old days this type of situation could suck the fuel tank almost flat.
Based on what I have seen I would advise you to look for a purge valve.
If this is a 3.6 they are usually located under the engine cover on toward the rear on the passenger's side.
You don't mention what year or engine you have.
I usually suggest to people to add the type of car you own to your profile in case you forget to post it in your query.
;)

It turns on the MIL (check engine light or Malfunction Indicator Lamp) because it can cause the vehicle to exceed EPA emissions standards.
It will draw in excess fuel vapors from the fuel tank which can affect the fuel mixture.

HTH
 

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Sedan de Ville, CTS
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P0455 is usually a loose or leaking gas cap.

On CTS a P0496 is likely a leaking purge solenoid.
The EVAP system has a vent, the tank, tubing and a purge valve.
The vent equalizes pressure between the tank and the atmposphere.
The Engine controller closes the vent valve during certain tests. On the tank somewhere there is a wein bridge type sensor (sort of like a MAP sensor) that measures the pressure inside the tank.

The P0496 test closes the purge valve and the vent valve and then watches the pressure sensor (FTP or fuel tank pressure sensor).
If the FTP measures a decreasing pressure during this condition it is flagged as "flow during non-purge".
Some older systems actually have another sensor in the purge line to detect flow by monitoring pressure (the old P engine in the RWD Fleetwood and F car is a good example).

Basically what it is saying is that the purge valve is leaking, this allows engine vaccum to bleed into the line and decreases the pressure in the tank. In the old days this type of situation could suck the fuel tank almost flat.
Based on what I have seen I would advise you to look for a purge valve.
If this is a 3.6 they are usually located under the engine cover on toward the rear on the passenger's side.
You don't mention what year or engine you have.
I usually suggest to people to add the type of car you own to your profile in case you forget to post it in your query.
;)

It turns on the MIL (check engine light or Malfunction Indicator Lamp) because it can cause the vehicle to exceed EPA emissions standards.
It will draw in excess fuel vapors from the fuel tank which can affect the fuel mixture.

HTH
Another job well done "by your treasury men in action." Anybody remember that from the TV in the early 50s?
 

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Sorry for the confusion, you can call me ewill, will or Bill.

I meant HTH, Hope This Helps. ;)
 

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Cadillac CTS 2003
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Hello,I do not mean to cut into this thread but I am having the same problem.Where is the purge valve located on 03 CTS 3.2 Liter?Thanks
 

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Cadillac CTS 2003
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Hello,I do not mean to cut into this thread but I am having the same problem.Could someone please tell me where the purge valve is located on a 03 CTS 3.2liter?Thanks
 

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Cadillac Technician
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I can't find a good picture or description but it appears to be located behind the right (passenger) side of the engine, maybe tucked in behind the cylinder head a bit.
It is hard to tell from what I see in the manual and I haven't had to replace on on the 3.2.
 

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Cadillac Technician
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I think you need the solenoid. What they are referring to as a "valve" is actually I think the vent valve.
That mounts under the car on the canister itself.
Too bad they don't have pictures.
I am sure that is true in fact. You could call a dealer to verify the part number.
 

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You are most welcome, and right back at you! Happy New Year, I hope it is a safe and happy one!
 

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I have the same problem and warranty is replacing the purge valve at a cost of $250.00. What detrimental effect is there if this problem was not addressed. Could I get stranded or could it hurt the engine in a more serious way? Thanks
 
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