When I get a P0456 followed by a P1111 does that mean it's now okay or do I need to fix something? Should I erase the code and see if it comes back?

 

P0456 is the fault code for a small leak in the Evap system. Normally, this system stops petrol vapours venting to the atmosphere.

You can get this fault code with a poorly-fitting petrol tank cap or a cap with a degraded seal. The fault can also be caused by the Evap purge valve under the bonnet leaking, or the connecting pipes leaking.

The first thing to check is the petrol tank cap...

The code P1111 is not a fault-it's just a code the system gives to show that the testing cycles of the engine management system have all been completed satisfactorily.

When you start the engine the system will show code P1000, which means that it hasn't completed the full set of system tests. When you go for a drive which includes all aspects of engine useage-particularly steady cruising & hard acceleration at full throttle to the redline-then the ECU can complete it's system testing procedure & will give the code P1111 to show that everything is alright.

P1111 is a good thing

P1000 means it hasn't yet completed all the system tests & you should drive the car further if you want to see the 'happy' code of P1111

 

I did get the P1111 code. I think I'll erase the codes and see what happens, sounds like P0456 isn't a big deal. Am I right?

 

P1111 is perfectly normal & will always show up after a drive if everything's ok & the system has completed all it's tests-otherwise it'll still show P1000. That doesn't affect the car in any way-it's simply a code to show all the tests have not yet been completed for this particular day's drive.

Yes, P0456 is not a big deal-it simply says that the Evap system is not holding it's pressure & that there is a small vapour leak from the Evap system somewhere.

The Evap system basically takes the petrol vapours that build up naturally in petrol tanks & stores them in carbon canisters, which are connected to an Evap valve under the bonnet. At regular intervals, the Evap valve is enabled & the stored fuel vapours in the carbon canisters are then passed through this valve into the engine to be burnt.

On the Jag, the carbon canisters are under the car at the back, just by the rear wheels-they are 2 rectangular boxes with pipes attached to them.

Code P0456 indicates that there is a leak somewhere in the Evap system-there is a fuel tank pressure sensor so any vapour loss causes a pressure loss which the sensor registers. It could simply be a badly-fitted fuel tank cap. Or it could be perished pipes to & from the carbon canisters, or it could be the Evap valve itself under the bonnet.

It's not really a big deal unless you have a big vapour leak & smoke by the car!

It doesn't affect the engine operation & is more of a nuisance than anything else, as if the venting leak is big on a hot day then you're losing petrol to evaporation.

 

Thank you for the great explanation.

 

The best bit is that is doesn't affect engine operation in any way-it's a secondary system & the worst it can do is illuminate the EML/MIL light, which would only cause a problem during annual emissions tests or MOT's etc.

 

I would bet my savings that this is due to a faulty gas tank cap!

Go to ANY smog testing station, and give a guy couple of bucks to hook up his gadget to your cap, and see if it's leaking. If it is leaking (I BET it is!) buy another one, clear the codes, and call it a day.

You can thank me later!

 

No emissions testing here in Florida.

I've had the Check Gas Cap message before, but not recently. Might be that, or maybe not. I won't worry about it right now.

Thanks for the help and suggestions.

 

Hi OldMike
Here is a P0456 forum thread that you should view:

https://www.jaguarforums.com/forum/x...ailsafe-60650/

Look at post# 5 and #9 and also #3

Jim Lombardi