P0455 Evap Emission System Large Leak
 

So i have been SES free for a couple of months now, and recently my Landy has been running kind of funny, so i've been awaiting the dreaded light to come on. Low and behold, today was the day. I scanned it as soon as i got home to find the code "P0455 Evaporative Emission System Leak Detected (large leak)".

What exactly does this mean? Has anyone ever had this problem before? And how would I go about tackling this problem? Thanks in advance everyone! :)

Check the gas cap?
Check hoses around filler tube?


luck,greg

I have had the 0455 code come on about every 2 months. My Discovery runs find with a strong idle and no fluctuation. I have the ScanGauge II, so I just reset it and roll on. I will check the breather hoses around the fuel filler area to see if I can find any loose or cracked hoses. I replaced the gas cap new from Rover about 1 year ago.
Dave

I have the same issue. I have had it smoked tested many times and tested from multiple shops. No one has found a leak. It does not seem to effect the way it runs at all. I think maybe I get slightly lower gas mileage now then before. I was told by the dealership that it is the pressure sensor on the fuel pump causing the problem. I reported that before but Disco Mike seemed critical of that possibility. At this point I am going to buy a fuel pump just to eliminate that possibility. If I can find one cheap enough that is.

im in the same boat. i get it from time to time. i replaced the gas cap.. checked for leaks. i have not seen it in a few months but it will be back soon... not worried as my MPG is great and she rungs good.

has anyone solved this yet? if i have time today i'm going to try and tackle it.

check the coal canister for rust, holes, loose connections or damage from rocks etc

if not check the purge valve up front, see if its clogged up with debris or stuck and if not, maybe the relief valve is in the rear

check the lines from tank all the way up

rave 17-2-3 shows a great diagram of component locations and line map.

I had the same issue with my Saab for years. I know it's not exactly the same system but it's close enough... Other than having to clear the CEL, it was no big deal and had no impact on performance. I eventually replaced the purge valve, even though it tested well and that took care of it. I surmise that it was an intermittent fault with the purge valve.

For any of you with a 455, if you can't find it go have a smoke test run and this will locate the leak real quick.

My next attempt was going to be replacing the fuel pump rubber seal, accessed at the top of the fuel tank. Its only $16 and figured from another poster on here he found his seal was crinked or turned under, so that was probably the leak. It would be an easy check by rolling up the rear carpet.