[burningmango]

Hi guys, my X3 xDrive35i has been dealing with this p0456 code for a while. For the past few months, I would randomly get a CEL with this code. But it has been off for a few weeks now and my registration (with smog) is due.

To my surprise, it failed the smog inspection with a permanent p0456 code.

I have replaced my fuel cap already and the permanent code is still there.

Before I start throwing money at parts for this, would replacing the tank breather hose (PN: 13907636135) and the leak diagnosis module (PN: 16137333301) make sense? What other parts should I consider or what is the likelihood of the cause of this problem?

[Bdavi011]

So I don't have the paperwork on me but I know the x3 35i had a recall for an emissions part. Google it and it should pop up.

I had an emissions code. Google it. Took it to dealer and got it fixed for free.

[burningmango]

With my research, I found this NHTSA service bulletin but it's for the N20 engine in xDrive28i models. And unfortunately, my X3 is already at 131k miles so I'm out of the extended warranty period anyways.

Last night, in the midst of the California storms, I replaced the NVLD switch. Now I will wait until *hopefully* the permanent code goes away after a few drive cycles. If not, I will resort to doing a smoke test for the Evap system.

[brianhinton77]

How did you read this code? I would try a specific BMW scanner for the ECU codes instead of the pcodes. The Pcode points to a few different things, but without drilling down further with iSTA, it could be the TEV, or DMTL

[burningmango]

Originally Posted by brianhinton77

How did you read this code? I would try a specific BMW scanner for the ECU codes instead of the pcodes.

I scanned using Bimmerlink and got 190302 "Tank ventilation and purge air system, fine leak: leak greater than 0.5 mm"

[brianhinton77]

Looks like this one points towards the TEV , maybe if you can get ista or a scanner capable of triggering components, you could run the DMTL test and see what happens. But it sounds like the tank vent valve is the culprit

[burningmango]

Thank you for all your replies!

Fortunately, I was able to resolve this issue and pass smog!

Here's a quick write-up on how I solved this because I noticed a lack of information on our specific F25 X3.

For context, I have a 2013 X3 xDrive35i N55 with 131k miles.

I can't guarantee this could be your issue as you could actually have a leak within your Evap system and not a faulty NVLD.

I replaced the Fuel Vapor Detection Pump, or some might call it the NVLD. Part number - 16137333301

#4 in this diagram


This part is located in the rear right passenger wheel well, right under the fuel fill port.

You have to remove the fender lining to have full access. Be aware that the clips that attach to the outer cladding are one time use only. So have replacement rivets handy. Here's a good video explaining how to remove the rivets effectively

Part numbers for replacement rivets:
White - 07147391323
Black - 51777171004




The NVLD is located in the yellow circle. The bracket is secured using two 10mm bolts. The electrical connector was a bit tricky because you have to pull a small tab before you can push down and pull it out.



I didn't feel like spending over $200 for a brand new NVLD but luckily my local BMW recycler had a fresh 2018 Alpina B7 with low miles that they were parting out and they share the same part for only the NVLD.



On top is the part pulled out of the Alpina and the bottom is from my X3. Swapping out just the NLVD was pretty straightforward, just a couple of T15 screws holding the parts to the bracket.

The dust filter and vent hose had to be removed. Removing the vent hose was a bit challenging due to them being a one time use clamp that is quite hard to clip off. Here's another video explaining how to remove them. I ended up replacing the clamp with a normal style hose clamp.

And that's pretty much it! I feel like the hardest part of this job was putting back the fender liner because you have to fight with it trying to get it back into the slots where the outer cladding meets.

I scanned for codes right after putting everything back together and the permanent code p4056 was still there. Also, it triggered a new code, p0450 or 194804 (BMW specific) but it was just the vehicle sensing that the NVLD was removed.

After driving for about 50 miles, the permanent code vanished and it was ready for emissions testing!

I returned the Autozone gas cap as that wasn't the problem. But I still highly suggest replacing your gas cap first as your first step in diagnosing this issue.

[Mmd]

I got this issue recently. For mine only one wire of the purge valve network was broken and there was a small leak (a broken purge valve can also lead to it, and cannot close the circuit anymore)

[almostZ4]

I'm having the same issue with my 2021 GR Supra, had the entire evap assembly replaced under warranty. After 1 month of downtime and parts replaced, the p0450 CEL and 194804 code came back with the helicopter noise.

Definitely not going back to Toyota. The code says open circuit. I had the car on a lift at a friends shop and we took the wheel fender liner off, unclipped the connector to the evap and clipped it back. The CEL went away and then back after 1 or 2 drive cycles. This this means there is an issue with the power cable somewhere. Where other than the connector would be a good place to check? Thank!