Charcoal Canister? Leak check pump? Vague code from Foxwell.

[rlordjr]

2001 540iT

I keep getting an SES and the Foxwell reads this code: 5D: DME: tank-venting system. OBD code is P0440/$11

No drivability issues like stumbling that others have reported. No gas smell after fill up.

Searching around the forums and larger interwebs does not reveal any conclusive information. Some reported fixing this by replacing the purge valve. I had a different code which was fixed by replacing my purge valve at which time I also got a new BMW fuel cap.

There are some more specific codes that can be read when the leak pump is dead but I just have the vague one that could be caused by leaks in the system, clogged canister, weak/dying/clogged leak pump, etc.

Anyone fixed this one in particular or have suggestions for easy tests to try? Some have tried smoke tests but this system vents to the atmosphere so you'll always get smoke out of the dust filter. Guess I could plug that and see if it smokes anywhere else. I'd attach smoke machine to the tube which goes into the purge valve to push smoke back to the canister and tank.

Other ideas?

Thanks

[m540isport]

May want to test if your purge valve is operating properly...Link below

https://www.youtube.com/watch?v=xw9NKLTqKUA&t=74s

[rlordjr]

May want to test if your purge valve is operating properly...Link below

https://www.youtube.com/watch?v=xw9NKLTqKUA&t=74s

Yep good Idea. I have also seen that it really only takes 9V to operate so I'll make sure it's working. I've definitely received defective new parts before.

[Chedley]

On the E39 540i, Code 5D = 93 (decimal) indicates a problem with the fuel "Tank venting system", and has nothing to do with the purge valve or the secondary air pump. Check your fuel pump / fuel lines and filter-regulator.

[rlordjr]

Thanks I will dig into this

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[rlordjr]

So I tested the purge valve with the scanner "active test" function. It makes the purge valve click on and off repeatedly. Not sure if that is what it should do. Should it just click open and stay open or cycle between open and closed? I also tested with a battery and it clicks when powered and clicks when power is removed. I did not take it off and blow through it when clicked for "open" just because it's a pain to remove.

Also tested the leak test pump (or solenoid) and heard it click and supposedly do its thing. If the leak test pump dies you are supposed to get a "voltage high" error on it.

Thanks to @Chedley for the above. I'm of the the mind that the purge valve has nothing to do with it and it is other parts of the fuel/vapor system.

The fuel filter/pressure regulator is only 2 years old. The pumps/senders/floats are all original but I have no fuel delivery problem symptoms. Well, I sometimes am skeptical of the fuel gauge but then when I fill up it makes sense. As noted I have no fuel smells and my nose is better than a bloodhound.

Maybe if it rains this weekend and I'm not in the garden I'll pull the purge valve and give it a complete test. And if I do that I'll smoke test the vapor recovery components.

Proceeding from simple to complex I would not be surprised if it was some kind of failed hose/line before it was something major like a dead pump or clogged/saturated vapor canister. Your #1 troubleshooting question is always "Is it plugged in correctly?" It applies to wires, hoses, pipes, etc.

[Yonkers320is]

Did you check the canister by the left rear wheel, underneath the whellcover? Has one blue line and a black line, they can crack and leak, and cause the 440 code.
Had it on my 528, glued a new plastic neeple and put a rubber hose between it and the plastic line and the code went away.


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[rlordjr]

Did you check the canister by the left rear wheel, underneath the whellcover? Has one blue line and a black line, they can crack and leak, and cause the 440 code.
Had it on my 528, glued a new plastic neeple and put a rubber hose between it and the plastic line and the code went away.


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I plan to look at that this weekend. I saw your thread about fixing that neeple. Nipple, neeple, whatever. I hope it is that simple.

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[Chedley]

....
Proceeding from simple to complex I would not be surprised if it was some kind of failed hose/line before it was something major ....

Check and replace the vacuum hoses from the purge valve to the manifold.

Buy a 2-foot of an 1/8 inch (3.2 mm) braided vacuum hose, and replace these hoses #9, 10, 11 and 12 in https://www.realoem.com/bmw/enUS/sho...diagId=11_2287 .

[rlordjr]

Check and replace the vacuum hoses from the purge valve to the manifold.

Buy a 2-foot of an 1/8 inch (3.2 mm) braided vacuum hose, and replace these hoses #9, 10, 11 and 12 in https://www.realoem.com/bmw/enUS/sho...diagId=11_2287 .

Good idea. I did have the code for "small leak <1mm" which I fixed by putting on the hose clamp I forgot to use when I replaced the valve. But those hoses have been baking for 20 years so it's probably time to refresh them.

[rlordjr]

UPDATE: finally replaced the vacuum lines under the hood even though they all looked great. Removed left rear fender liner and visually the expansion tank and canister look super clean. Hoses and connectors back there look great as well. Activated the LDP and solenoid with scanner and they seem functional. Unplugged connectors here and there and shot them with cleaner. May need to retest the purge valve and the other valve on top of engine. Started to test more and then my back said "hell naw". Knew I should have asked for help putting on that wheel.

[rlordjr]

Hoses1.jpgAn update to note that I replaced all the underhood tank evap hoses except one and then I replaced that one and found a likely culprit. Pictures show bad hose and good hose and then bad hose and good hose after being pinched. Hopefully its all good hose now and the SES light won't reappear for this reason for some time now...Hoses2.jpg