[Xerix]

So last fall my car was throwing some temp sensor and level sensor codes:
46F9, 492C, 4BAC, 4D32

Basically the temperature sensor and fill level sensor were failing. If the active tank was full, no code would be thrown.

So this spring I started doing more research and found a company called Xemodex based out of Mississauga. They sell a kit to replace the Heater, Temperature Sensor, and Fill Level Sensor. I got it for $549.99 + tax from them, but I picked it up myself.

So I have to say first that Xemodex provides very good detailed instructions on which wires to cut and solder, but not on how to get to the tank guts. So these instructions will only focus on getting to the tank via the trunk. These instructions do NOT require you to remove your tank.

Instructions
1. Securely put the rear of the car up on jack stands.
2. Ensure your urea tank is not full! If it is than you will need to empty it. I did not have to do this so I don't have the instructions. Mine was already showing me my 1600 KM no start warning for about 400 KM, so it was not a problem for me. If your warning light has not come on, then it will pour out of the tank when you open the nut on the tank later!
3. Remove the 6 rearward retaining brackets that hold your exhaust to the car. I specifically unscrewed the bolts and nuts from the frame and swung the brackets away. I did this by starting just aft of the center brace just below the passenger seats and worked by way to the back of the car. Before you unscrew the last 2 screws under the bumper, make sure to have a small car jack against the exhaust so it does not fall. It is heavier than it looks.
4. Unscrew the heat shield above the exhaust. Half of my screws had rusted away and were no longer there, and I broke 2 more because they were so badly rusted. You do not need to remove the smaller heat shield close to the center of the car.
5. Do not remove the heat shield as you do not have to. Just let it drop down on the exhaust.
6. You will now be able to see 2 bolts that are holding the urea tank to the back side of the trunk floor plate. This space is just enough for you to get your hands in to get access to the 2 bolts the tank is hanging from, but do not remove them yet.
7. Under the passenger side just forward of the rear wheel, there is a plastic retaining nut against the trunk plate you will remove. This simply holds a plastic cover to help protect the positive battery cable. Unscrew and set aside. You will not be able to remove the plate in the trunk without removing this nut.
8. Unscrew the 2 nuts holding the urea tank to the trunk floor. You can slide your hands in under the bumper but above the heat shield to get to it. Where a long sleeve shirt so you don't scratch or cut your arms when sliding them in. The tank shouldn't drop out because it still has 2 brackets towards the front of the car that will hold it in place. Worst case it might swing down toward the back.
9. Remove the carpets from both sides of the car in the trunk and remove the plastic cover around the trunk latch. There are a couple screws and plastic clips that will need to be pry'd out to do this.
10. Unscrew the 10 floor plate nuts from within the trunk. The plate is sealed with a rubber gasket that sticks to the surrounding floor, so you will need to gently pry it up away from the car around its perimeter. I started from the lip at the back of the trunk as it was the easiest. While prying the plate up, the standoffs will most likely hang on the tank, so you will need to use one hand to pick up the tank to take the weight off the threads, and then pick up the plate. The plate is heavier than it looks, so be sure to have a good grasp on it. I actually wedged a piece of wood to hold the tank up and removed the plate with both hands as it was easier.
11. You now have access to the guts of the tank with the sensors and heater in it.
12. I used a big C clamp (Welding Joining Tool) to unscrew the ring off the urea tank. Because this part is recessed into the tank, you have no space to get a wrench or channel locks around it. Thats why I used the clamp I had which fit very nicely over it.
13. Disconnect the wires and urea outlet line and remove the pump. I set it aside and cleaned it later making sure the small O ring was still attached. If it isn't, then it is probably still in the inlet on the tank. I covered these holes so they would not dry on me and possibly crystallize. You can also flush it with water just to be safe and still cover it.
14. When I got the plastic ring nut off, I removed the rubber boot as instructed by Xemodex.
15. I then put my hands into the tank and put my hands on the level sensor and turned counter clockwise. It turned maybe a quarter inch and came right out. Mine turned easily, but the Xemodex instructions state that it could be very stuck on and wont turn easily.
16. Follow the Xemodex instructions from here on out and follow the procedure in reverse order to get it all back together once you have soldered your new parts into the existing wire harnesses.

Images
Lowering Exhaust (6 Brackets)




Battery Cable Bracket (1 Plastic Nut)



Access To Nuts From Under Tank


Access To Sensors & Heater From Top of Tank


Clamp to Unscrew Plastic Ring


Soldering Wires - Mesh Them Together On End Instead of Twisting - Shrink Wrap Is Slipped Over Wires Out of Frame.

[apexit4]

I wish I had this procedure a little over a year ago. I ended up buying a new tank (before the recall). Thanks for sharing the info with us!

[floydarogers]

Very nice!

Looks like Xemodex pulled together several of the known (but ill-documented) fixes.

[ranthum]

If anybody reading this needs parts, my tanks were removed a few months ago. Shoot me an offer on whatever you need.

[grotto]

This is a great write up, about to do this myself. Why couldn't they have made it where we could remove the top cover easily. I think BMW does this on purpose to get more labor fee's.

[DougNBodie]

The SCR heating element and level sensor is avail. at FCP Euro for just under $450.00 and that comes with a lifetime guarantee. No need to buy a new tank. Easy fix.....Or so I thought, Codes cleared and SES light went off immediately but came back on after about 10 miles. Anyone else run into this problem