Bought my 2018 Macan from dealer inventory and it was missing three options I wanted. Two of them, Apple Car Play and Sport Plus Mode were easy as the parts and activation codes were readily available from Porsche, although it often takes some dealer education to get them installed. The last item, heated steering wheel, is not so easy. Porsche will not support installation of a heated steering wheel unless it was included as a factory option. There is some good information in other posts about how to do this yourself but it was never really clear which parts must be replaced and how to accomplish this retrofit with proper activation coding.
First off, before working on sensitive components like airbags, etc, you should download the appropriate Macan Service Manual. I downloaded a PDF of the manual for about $30 and it was very valuable. The two components that need to replaced are the steering wheel as well as the clock spring which resides in the steering column just behind the steering wheel. The activation coding needed for the heated steering wheel to work resides in the steering wheel control unit which is mounted in the heated steering wheel below the center hub of the wheel.
The key to this project is obtaining a used steering wheel that was coded at the factory for the steering wheel heat option. You need to ensure the wheel you buy matches the options in your car. Most Macan's have similar steering wheel functions such as PDK paddles, and multifunction controls, but some new models also have PASM controls on the wheel, so you need to ensure the wheel controls looks exactly like yours. The wheel I purchased on eBay was about $800 and came from a Cayman. Caymans, Boxster and Macans (and other models) use the same steering wheels. eBay listings often include a compatibility list which is a good start, but be sure you are getting a wheel that matches your car. My base Macan has the standard leather wheel so finding a used one with heating was not difficult. Unfortunately the wiring harness on the one I purchased had damaged connectors so I had to replace the steering wheel wiring harness. This was actually good as the process of replacing the wiring harness was a great way to understand how the wheel is wired. (Seller paid for the new harness)
The replacement clock spring is necessary as the one installed by Porsche for non-heated wheels does not have the electrical connections installed to supply power to the wheel heating circuit. There are a lot of clock springs available on eBay so make sure the one you select has the electrical connection for the heated wheel. This connector is at about 8 o'clock on the face of the clock spring and has two contacts. Most sellers will be able to verify the donor car was equipped with a heated steering wheel. Note, the electrical wiring harness for the heated wheel from the fuse box to the clock spring is installed on all Macans so no further wiring is required.
I will not detail the full procedure for changing these components as the service manual is pretty detailed and easy to understand. However, there are some important things to note. Be absolutely sure to disconnect the battery negative terminal (in the boot by the spare tire) and wait a few minutes before you begin the process. Removal of the air bag module is actually simple. If you have your new wheel without an airbag installed you can practice using a narrow screw driver to release the clips. Be careful in removing all the electrical connectors to insure they're not damaged. The connectors all have different release mechanisms so make sure you study each one before releasing it. The steering wheel has a mark that allows you to align it properly with a mark on the steering shaft. The new wheel should be oriented to match the relationship of these marks.
To remove the clock spring you need to remove the plastic shroud around the steering column. The top part simply pops off and the bottom is held by three screws; two on the front at the top corners and one underneath. The one underneath is accessed directly if you have a manual adjust column or by removing the column adjusting switch if you have the memory package. The clock spring is held in place by a tiny silver screw at the bottom in the center and two clips at the top. (Work the top clips off gently so you don't snap them off.) The clock spring has a coiled ribbon of conductors inside its case. This ribbon winds left or right when steering to accommodate the steering wheel position. This is simply the modern way to maintain all the electrical connections on the wheel. You need to ensure the new clock spring was actually centered when it was removed from the donor vehicle. The case is transparent so you can make sure it looks the same as the internal coil on the one you removed. If you want to physically check it, you can depress the button on the front and rotate it fully in one direction then the other way while counting the number of turns. Then simply wind it back half the number of turns to make sure it's centered.
Reassembly is simply the reverse. Make sure you securely fasten all the electrical connectors to the clock spring and they lock in place. When replacing the steering wheel, orient it to the mark on the steering column and make sure the upper electrical connector and the heated steering connector are firmly in place before screwing the wheel in place. (Porsche actually calls the steering wheel nut a "steering wheel screw".). The proper torque is listed as different values in different places but the service manual indicates the initial tightening is to 30 NM and the final tightening is to tighten it another 90 deg's. Strange but that's what they recommend. Also, be sure to securely fasten the two air bag connectors. Both of them have a tab on top that must be popped up before removal. When the connectors are firmly in place you push down on the tabs to lock them in place. Some people have not attached the air bag connectors properly resulting in air bag faults. BTW, Porsche strongly recommends using a new steering wheel screw each time it is removed due to fresh thread locker on the new one. If you have your tools ready to go the entire process should take less than an hour. It is not difficult, simply one that you want to do slowly and carefully.
As this process requires there can be no electrical power to the car, disconnection of the battery will cause the car to forget certain settings. When you finally restart the car you will get error codes related to the battery disconnect. This is completely normal. People have reported different error codes but mine Indicated 1) PSM Failure, 2) AWD Failure, 3) Lighting system malfunction and 4) Limited steering system support. In addition the auto start/stop was deactivated and the Hill Descent button did not function. Literally all of these error codes are related to the need to recalibrate the steering angle sensor.
You can have the steering angle sensor recalibrated using the OEM Porsche diagnostic tool, or an aftermarket code reader such as the FOXWELL NT650. My recommendation is to take the car to an aftermarket garage specializing in Porsche maintenance and have them do it. It takes about 5 minutes and most garages charge only a nominal fee or nothing at all. In my case the local dealer indicated the codes could not be removed and so they were not able to correct them. Per the dealer this was because my car was not built with heated steering. One of the service reps told me quietly to take it to a local garage as they're much more "flexible" than the dealer who is under Porsche control. I did that and it was corrected in 5 minutes. The shop tech simply shook his head about the inability of the local dealer to accomplish this simple task. Chalk it up to OEM politics.
So, long story short my 2018 Macan now has fully functional steering wheel heating and operates perfectly.
Note that pretty much all Porsche cars are spec'd differently so there are endless variations that could affect this process. My car is a base Macan. but I spent a good deal of time researching the process which worked for my car. In addition, you will be banking on the fact the steering wheel you acquire was coded properly at the factory and is still fully functional. Most of the used steering wheels available are from donor cars that were scrapped and likely experienced an airbag deployment. So there are risks. However, that's part of the fun. It's a great feeling the first time you hit the heated steering wheel button and the multifunction display pops up with the message. "Heated Steering Wheel On".
Good luck with your project if you decide to give it a shot!