This is a lot easier to do with the car jacked up even on one side. Remove the 3 pop fasteners using a flat screw driver. Remove the small nut that hold the fabric in the wheel well behind the well, this will give easy access to other bolts.
Note I have aftermarket splash guard so my setup looks different. Repeat this for the other rear wheel. The wheel does not need to be removed, a short flat screwdriver will work just fine or come in from under the car.
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| Remove pop fasteners |
Remove the two bolts from under the bumper behind each wheel. This needs to be repeated on each side.
I have a splash guard, so my setup is different, but same bolts need to be removed. Repeat for other side.
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| Remove bolts behind wheels |
Remove the bottom hitch cover by turning the plastic screw 90 degrees counterclockwise and remove the cover. Then using a flat head screw driver pop the two screw covers.
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| Hitch cover removed and cover screw popped open |
Next remove all 100mm bolts securing the rear diffuser. 6 bolts that hold the diffuser to the body. 3 bolts are indicated in the picture above, and 3 more that are shown in the picture below.
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| Remove diffuser screws |
There is another screw under the fabric, between the 2 bolts shown in the picture for which you will need a flat wrench. See picture below.
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| Remove hidden screw |
There are two more bolts inside the rear bumper that need to be removed. These can be reach from inside the hitch opening or from the rear fabric cover of the rear wheels. No These bolts that are in the picture below but ones that are father along the inside on both side.
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| Not these bolts, ones that are further in. |
Remove these bolts. you can either work a 100m ratchet wrench in there or come in from the wheel well using a socket and extension.
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| Remove these bolts from inside |
The tabs are next. If you pull on the diffuser at this point, it will rip off the entire bumper or at least bend the mounts so that the bumper will end up having gaps to the body. What needs to be done at this point is to carefully look at each tab and you need to pop the tab out of the bumper trim piece and separate the two. A firm push with a flat head screw driver will achieve this start at one end and work around the bumper. It maybe useful to put a bolt back to hold up the diffuser so it does not hang and pull on the bumper.
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| Each tab must be released properly. |
Another gotcha is that when assembling the entire diffuser, these tabs must be popped back, not just slide back into place. You must pop them back from inside the bumper. I am willing to bet that ton those Model 3s which have had their bumpers and diffusers fly off on the highway or in rain, did not assemble thing properly. The diffuser then comes off easily.
The amount of dirt in my Tesla's rear diffuser with just 4300miles of city and highway drivng was this much:
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| That's a lot for just 4300 miles of clean driving. |
At this point you from removing built up sand and dirt as well as a chance to add more water drain holes. See my post about that here.
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| Time to clean and make extra drain holes in diffuser |
That this point, depending on your need for rear diffuser removal, you can either work on spring or drill more holes of clean and replace.
To reinstall the diffuser. Make sure all tabs slide into place correctly. Lightly thread all the 10mm bolts that were removed. This is not a Lego set so nothing should be extra left overs.😁 Use a flat screw driver from inside the wheel well and from the hitch opening to secure all the diffuser tabs. Tighten all the 10mm bolts. Don't forget the bolt that is under the fabric undercover. Replace all 6 of the pop fasteners in the wheel well.