Per Brutal, he says it's never been the cap. He says a cap gives a large leak not very small or small.

 

I'm pretty sure it's not going to be the gas cap either. I do not hear a vacuum sound upon opening the cap.

For the time being I bought a new code reader (gave the last one to my son), and I just cleared the P0456 code.

Is just clearing it once every 3 months and ignoring it a bad idea?

 

Per several member techs here, they told me it does not affect anything on the car or cause a future problem with any part or component., It's an environmental requirement. I cleared mine for over a year until I couldn't.

Like Jay Leno relates. A brand new 1960's car, sitting still, not running, emitted more pollution than a modern car sitting idling or driving down a freeway.

 

yep you dont need to drop the tank to replace the tank seals or epoxy the center evap loss tank valve. Just need a cutoff wheel . Remove the back seat and cutout the floor to access the top of the tank in entirety. Just be carefull of wires and lines.
(disclaimer. That is sarcasm before someone does this as says i read online to do this by a tech)

 

I got the P0442 again and reset the code again Friday. It seems like it occurs every 3-4 months.

I also noticed today that putting gas into the car seems to be getting increasingly hard.
The pump constantly shuts off - at least 20-30 times during the fill-up - unless its held to run at a trickle.
I bet the air can't get out of the tank leading the gas to back up in the filler tube and the pump thinks the tank is full and kicks off.

Dell - was yours doing that slow fill-up thing too?

Pretty aggravating that it is clogged and kicking codes when she has only gone 21,000 miles.

 

No, mine never had the filling problem but, look up in search that problem and there are a bunch of threads with discussion and fix.

 

The 0442 and 0456 codes got more frequent, as in once a week or so.

Took the car to my indy mechanic to see if he could address it. He smoke tested and checked hoses and valves, but couldn't identify issue.
Since he didn't fix anything he didn't want to charge me. He recommended changing the gas cap.

There was a little voice in the back of my head... "Brutal says it's never been the cap"

But I bought the dang gas cap anyway since its the easiest and cheapest possibility to eliminate. The cap was $14.

First thing I noticed in taking off the existing cap was that the retainer pin that holds the cap strap to the body was shot.
Its one of those teentsy push-in plastic rivets, and 3 of the 4 expanding tabs were gone, so it was already loose.
And of course the new cap did not come with a new retainer pin.

Then I noticed the new caps thread pattern was different - as in it had screw threads on it - whereas the old one had a a "D" shape with a half-a-thread on either side instead of threads.


New cap on left, old on right.

The new cap does seem to screw in MUCH tighter than the old one. That's a hopeful sign.

The rubber gasket at the base of the old one looks pretty "tired" too.

Its only been on there for about a week - so I can't call it "fixed" yet.... only time will tell.

And I ordered the stupid little pin. They charge $14 for that tiny little item.

 

I went to AutoZone and bought a package of the pins for like $4, lol. I originally just removed and reversed the gas cap gasket. That worked for about 2 months but, with my problem being the dumb rubber hose section on the fill pipe, it probably just made that part failure more persistent.

Brutal didn't say gas cap never a problem, just that it was a large leak (different code = p0455).

 

The verdict is in.
It is not the gas cap.
0442 and 0456 codes are back.
Still very difficult to put gas in the car.
Gas backs up the filler tube and pump chokes off constantly.
I think it has got to be related to that, and I'm suspecting the rubber vent hose alongside the filler tube is clogged or pinched.
Since I'm not going to drop sub-frames or gas tanks myself, its off to the shop we go.

 

Most likely purge system vent valve (also called purge system solenoid) right next to the charcoal cannister, part C2S8605.

Read post #25 =

https://www.jaguarforums.com/forum/x...s-93916/page2/

 

First trip to the shop replaced the purge valve in the engine bay. Vapor Canister Purge Valve C2G2403
They also changed the filler cap again, back to the "D" threaded style. It passed a smoke test.
But the 0442 and 0456 codes were back two days later.
Second trip to the shop replaced the Vapor Canister Solenoid C2S8605 down by the fuel tank.
The codes came back a week later.

Still have the slow fuel filling problem.

 

Doubt they did a good smoke test. The very nature of those codes are showing system falling "pressure" test of some area of the system.
ADDITIONAL THOUGHT =
If the "shop" you took it to does not have the appropriate Jaguar diagnostic software to be able to "manipulate" the appropriate modules, that could account for them not being able to get the smoke to leak from the problem area.

You have to take into account HOW the system attempts to determine EVAP system integrity. Cars up to 2006 MY all use the engine and it's manifold vacuum to do the test. That is, the ECM closes off the vent system, then APPLIES manifold vacuum to the tank by opening the CANISTER PURGE VALVE. Then it closes the Purge Valve an sees how long the vacuum takes to trail off. If it looses it quickly, it ASSUMES a big leak; looses it slowly, it ASSUMES small leak. Now, if it NEVER sees the vacuum at all, it ASSUMES what they call a rough leak, and sometimes says "check gas cap". In all cases, the fault is for a leak, but as I said, it may not be a leak at all. It may be a failure of the TESTING MEDIUM, vacuum.

By the same token, a failed vent valve that won't close properly for the test, results in the same thing; a fault for a "leak" because it can't hold vacuum for the test

The code P0455 and P0456 is flagged when the computer detects a leak in the EVAP system. What's the EVAP system? In your fuel tank while you drive the car and move the gasoline around gases form. Now by law this gas cannot be simply released into the atmosphere, so the car uses the EVAP system to store this gas and eventually (when the moment is right) feed them to the engine. The computer monitors that this system doesn't leak, and this code is flagged when the computer sees a problem. The computer has a little pump that creates a vacuum in the system, then with a pressure sensor sees if the vacuum stays. If the vacuum doesn't stay the computer flags this code.