So let me start by saying that I've probably read every p0440 thread online and gained a lot of knowledge by doing so, but not a solution.

I have a 2000 Discovery II w/ 164000 miles and I'm popping the p0440 code. I started by changing the purge valve, light returned, changed the charcoal vent solenoid, light returned and I changed the gas. I took the rover to a buddy's shop and they ran a smoke test on the evap system and didn't find any leaks.

Any ideas on where I should go next?

Your assistance is greatly appreciated.

 

I am having the same issue along with a "semi-rough" idle. Have an '03 Disco 2 97k miles. New purge, new leak detection pump (mechanic says it wasnt pulling a vaccum) and smoke test showed no leaks. The P0441 code has come back along with a KAM code as well. ANY IDEAS????

 

are you using a Land Rover specific code reader?

Never heard of a "KAM" code.

 

Fuel cap seating all the way? Sometimes you have to clean the threads in the filler neck. Also what brand purge control valve? I only use genuine Hyundai in a sealed Hyundai box/bag or the OEM Bosch unit. Aftermarket are not reliable.

 

Purge is OEM Bosch. He tested the purge for correct functionality and it wasn’t stuck open and could manually close it with his comp. He replaced the leak detection pump for emissions system.

The KAM (Keep Alive Memory) code is what he told me this morning is showing up.

P0603- lack of proper voltage to the KAM connection on PCM, defective KAM, def PCM ground circuits, or def PCM controlled output devices

 

I do a lot of evap leak repairs, hopefully some of this brainstorming will help?

Another thing to try with filler cap is rub Vaseline on the gasket. My gas cap tester is older and doesn't fit the newer style caps, so now I do that first, clear fault and send customer on their way. If it fixes, I have them replace the cap.

Sometimes I have to smoke sections individually. I'll take a section and plug one end and isolate it from everything else. For example the canister system, I'll take each end of lines off and just do those lines individually. While I'm there l, depending on what kind of vehicle, I'll either command the purge and vent valves or just bench test them. You have to test them repeatedly, they can fail once or twice in testing them 10 times and that enough failure to set a code.

Where I am in the rust belt, I get a bunch of evap leak codes that end up being the metal lock ring of the fuel pump on tank rusted out and allows vapor leak. This one sucks to find as it's often too small a leak to show a fuel trail and a lot of tank strap fasteners are rusted out and have to be cut off and replaced. But it's one of the more common ones when someone has been to many shops with no answer.

Another annoying find is multiple tiny leaks, for example a bunch of cracked small vacuum lines leaking and adding up to finally setting codes. Now I just replace vacuum lines as I smoke.

​​​​Another common leak area I like to isolate is all of the vapor lines along the frame from tank to engine bay. Even the plastic/nylon ones can have cracks or get rubbed and cause a hole.

I use stick cameras to watch the top of the fuel tank where the lines come in and out of tank and filler neck. It can take a while.

​​​I also use scented baby oil in my smoker. The leak may be too tiny for smoke to show up, but you can smell it and start focusing on one area.

​​​​​Most of the cars I work on are 15 years old with well over 150k and I'm in the rust belt which adds to the mix. I'm in NJ which has emissions inspection, and there are no waivers so you either fix it for your sticker or get a new car.

Hope you find it, I know these are one of the most frustrating to find!

 

Do you know which type of evap system you have? Vacuum or positive pressure? Have you read the RAVE manual section on the evap section?

 

I am not 100% sure what evap system I have but I want to believe it’s vacuum because theirs a leak detection pump that pulls a vacuum??

Thanks for the advice guys. I just recently replaced gas cap back to the one I originally had on there before all this started happening. Had recently bought new one from Oreillys. But the semi rough idling has lessened since swapping caps and no evap light in 100 miles so fingers crossed.

 

If there is a filter in the engine bay near the firewall and a pump next to the EVAP canister then it's a positive pressure type system. If there is a device at the firewall and no pump next to the canister then it is a vacuum type.