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1995-2002 Range Rover P38A
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Discussion Starter #1
Hello again guys, 2001 4.6 HSE CEL came on OBD2 reading P0455 (Evaporative Emission System Leak Detected - large leak) - no other codes

When I was replacing the throttle body heater and was removing the intake hose, I snapped the little plastic bits that the clips hold onto and botched the repair with homemade gaskets and cable ties seems very solid--- CEL came on several hundred miles later so not sure if related

My question is do I focus on the air side of things i.e. vac lines, possible offending intake hoses, or start replacing fuel lines, gas cap, etc.

Vehicle runs and drives perfect, plenty of power

Thanks everyone - also, glad to be back forget my password and got it back through the moderator!
 

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1999 P38 HSE 4.6 THOR
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Watching this one as this is the only code I've yet to clear. It doesn't seem to affect anything else in several thousand kilometres. I've read the other obvious threads and so far I've changed the purge valve, the gas cap gasket to no avail. As an aside, when I do clear the code, it takes a few days for the CEL to come back.
 

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1995-2002 Range Rover P38A
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Since you have a probable cause (your repair) and an issue that would certainly appear to be related to this, I would start by sourcing the proper clips and seals (Possibly from a wreckers?)
Beyond this, have you made sure that the filler cap is indeed screwing on all the way to the O ring seal before it ratchets? I had one that was tight and leaked like a sieve unless carefully, and fully screwed on.....
Also, make sure you have not knocked off any of the other, smaller lines somewhere under the bonnet whilst you were in there.
 

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1995-2002 Range Rover P38A
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Discussion Starter #4
Watching this one as this is the only code I've yet to clear. It doesn't seem to affect anything else in several thousand kilometres. I've read the other obvious threads and so far I've changed the purge valve, the gas cap gasket to no avail. As an aside, when I do clear the code, it takes a few days for the CEL to come back.
Same scenario here, if I clear the code it takes a couple days (100 miles or so) to come back on

I will check the gas cap seal and look around for other lines tonight.
 

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JACK'S GRANDAD
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Why would you change gas lines?
RAVE has a description of how it all operates. If you dont understand it, then read that.
First thing to do is undo the bodged connection. Get the right bits before looking for other stuff.
I guess I just dont have the imagination to picture zip ties securing a EVAP line correctly.
EVAP faults dont normally come up right away. SO you driving a while before it triggers is normal.
Common sense tells me that if you didn't have the code before hacking the broken connection, but did afterwards......Then the connection is a likely suspect.

Martin
 

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1999 P38 HSE 4.6 THOR
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I've read through the RAVE - Fuel system - Tank leakage detection system, and it seem like a relatively small system of components. I'm guessing that by the use of the term "large leak" it means the leak is bigger than 1mm as per the metering orifice (if the system pumps more air than the .5mm orifice will allow, it determines there is a "large leak" in the system.) There is also an explanation in the RAVE about why this error shows up after a period of time. There are parameters that the ECM uses to do the leak analysis, ie: every second time the engine is run more than 20 mins etc... The connections for the evaporation system, the fuel cap, the purge valve, the fuel filler neck are all spots that could produce a leak larger that .5 - 1.0mm. Happy hunting to us!
 

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1995-2002 Range Rover P38A
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Discussion Starter #7
So am I correct in saying it could be air intake related or fuel system related, but not vacuum related? I have mended the botched repair of the connection between the MAF and the airbox. O ring was not seated properly. Cleared code and it has yet to reappear but I suspect it will and this was not the problem.

If an air leak was present in the system before the MAF, it wouldnt affect the MAF's readings, correct? This is what makes me think that wasn't the issue.

I will look through RAVE later today, thanks!
 

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1995-2002 Range Rover Classic
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So am I correct in saying it could be air intake related or fuel system related, but not vacuum related? I have mended the botched repair of the connection between the MAF and the airbox. O ring was not seated properly. Cleared code and it has yet to reappear but I suspect it will and this was not the problem.

If an air leak was present in the system before the MAF, it wouldnt affect the MAF's readings, correct? This is what makes me think that wasn't the issue.

I will look through RAVE later today, thanks!
a large leak in my experience normally has lead to a fuel cap with a worn out seal, sometimes a little wd40 on the cap seal goes a long way to diagnose this code. other wise could be a punctured breather pipe or missing fuel cap. often a shop with smoke machine and or nitrogen leak finder system can pinpoint fault.
 

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1995-2002 Range Rover P38A
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Discussion Starter #9
100 more miles, still no CEL, not really sure what to look for on the filler cap - looks pretty normal to me
 

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1995-2002 Range Rover P38A
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Discussion Starter #10
Another 100 miles, engine has been started and shut off several times, still no CEL. Starting to think it was that o-ring connection
 

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1995-2002 Range Rover P38A
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Discussion Starter #11
Good ol P0455 returned today, put new gas cap on, cleared code and waiting to see if it returns...

the adventure continues!
 

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1999 P38 HSE 4.6 THOR
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Good ol P0455 returned today, put new gas cap on, cleared code and waiting to see if it returns...

the adventure continues!
I bought a new gas cap but only harvested the o-ring off the cap so I could retain the tether on my original cap... P0455 returned. I'm not hopeful, but I'm going to put the new cap on a see if that makes any difference. I suppose slightly worn threads on the cap may provide slightly less clamping force.
 

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1995-2002 Range Rover P38A
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Discussion Starter #13
Yea I expect mine to return, the old cap appeared to be in good condition. I'm going to inspect the lines and connections at the charcoal canister before replacing the purge valve. However I would imagine the purge valve would trigger a small leak.
 
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