So I just got a 2004 LR Disco 2 88,000 miles and trying to get the inspection done but ran into some problems....

on my way to the inspection station, I kid you not, the check engine light came on. I went straight to my local auto parts store and checked the code it was the gas cap code. (P0455) evaporative emission system leak detected gross leak no flow. Well I had them clear the code and tightened the gas cap. Well not knowing the vehicle needed to be ran through a drive cycle I went straight to the inspection center and of course failed the inspection. I ordered an OBD I’ve now driven about 100 miles and still show “cat” not ready “evap” not ready and a new code!! P0135.

Any ideas on what could be going on.... new to the Disco community so hope this isn’t a rookie problem but if it is I’ll consider it a part of my initiation.

 

It takes a long time for the system to become ready again for test after resetting codes. Also, the plastic threads on these gas caps have a tendency to swell over time, so you may think the cap is on tight but the rubber gasket may not be sealed against the metal on the filler neck. Spray a little WD-40 on the plastic threads on the cap and make sure it's screwed down tightly. Alternatively, get a new cap - the OEM Rover gas caps are only like $10.

 

Okay, I’ll buy a genuine one just for piece of mind... I know the previous owner had the same issue with the gas cap and they replaced it with a after market one. Thanks if anyone else has any ideas I’d greatly appreciate it.

 

So I finally got through my drive cycle but the dreaded p4055 code still popped up everything else showed clear.

Any suggestions?

mechanic said try replacing the charcoal canister???

 

could also be the purge valve. there is an inexpensive Hyundai purge valve that will work. can't remember the part number.

 

The OEM units used to be nothing more than a rebadged STANT gas cap with a lanyard on it. You can still to this day buy a 5.99 STANT gas cap, pop the top off, swap over the new guts onto the old cap top & keep the LR Logo & the lanyard.

 

So I just left the the rover shop and they suggested a fuel filler neck pipe ... which is apparently not made anymore. Said if that’s not it maybe the gas tank.

anyone ever had to replace this part before?

Part number WMJ500140

 

You need to perform a smoke test, also is your D2 SAI Equipped or non SAI? Could be a bad line, canister down by the TC, or the vent on the fuel pump

 

Cleaning the inside of the fuel filler neck neck pipe worked for me... As suggested by a forum member, use a scotch bright pad and make sure to scour all around the ring just inside the lip where the cap threads onto. I found scale buildup on the lower side of that ring which when removed helped seal my cap.

 

Okay I’ll try that this weekend


will the code clear on its own or should I clear it and do another drive cycle after?