I had the check engine light come on- code P0456(I think) very small evaporative leak-checked the gas cap and it would no longer lock on - ordered a new one and it also does not lock so I am thinking it might be a problem with the filler tube-anyone had this issue? Thanks

 

Same thing happened to me last year. Check gas cap light came on and wouldn't stay off.

My local mechanic replaced the cap and it has been fine for about a year. This past weekend the light came back on and is now behaving like it did last year.

Anybody got any ideas for why a gas cap seems to have only sealed for a year? Or did the new cap mask some other underlying problem?
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Jaguar: Grace, Pace, and Space - Sir William Lyons
2015 JCNA National Slalom Champion Class M
Current: '08 Jaguar S-Type 4.2 "Satin Edition" (250.06 whp / 259.67 torque)
Past: '05 X-Type 3.0/auto Jaguar Racing Green

 

The most common cause for P0456 is not the gas cap.

 

>The most common cause for P0456 is not the gas cap.

Ok, my yellow warning light is on and the message displayed is "Check the Gas Cap", so this might be difference.
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Jaguar - it's not an automobile, it's a Motorcar
2015 JCNA National Slalom Champion Class M
Current: '08 S-Type 4.2 "Satin Edition" (250.06 whp / 259.67 torque)
Past: '05 X-Type 3.0/auto Jaguar Racing Green

 

Stopped by my local mechanic this morning and he used his code reader to see a P0456 code (displayed as "small evaporator leak" or something like that), so that is the cause of my "Check Gas Cap" warning.

Does anyone know what's the most usual cause of that code?
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You dreamed of a big star -
He played a mean guitar -
He loved to drive his Jaguar...

So welcome to the machine

 

Quick search reveals dozens of threads including this important one

https://www.jaguarforums.com/forum/s...76/#post277647

This is what I was alluding to with it's 'not the gas cap', at least with my car.

 

>P0456 Evap Small Leak - But not really?

Yes, and in surfing around today this is what I have come up with (and it agrees with "kit" replaced in the link above:

From: https://www.jaguarforums.com/forum/x...de-p0456-6423/

Code: P0456

Do the gas cap first
if after that you still have an issue it may verry well be a canister close valve
if you end up doing the CCV make sure you replace the pipe as well
it runs between the 2 charcoal canisters
the pipe is usually the culprit due to moisture and then rust
that rust ends up getting into the CCV valve and keeps it from closing completely

I recently had the same issue, although my code was PO455. Tried the Gas Cap first to no avail. The new Canister and upgraded Vent Tube Kit took care of the problem completely. All in all, it wasn't too bad.

P0456 OBD-II Trouble Code, Evaporative Emissions - Jaguar

MOST LIKELY CAUSE:
First of, if you haven't already change the fuel cap.
Then just clear the code and see if it comes back. I changed countless fuel caps over the years.

If that doesn't work, you might want to look at the canister close valve and the canister purge valve. This are very common as well.