Hey everyone! I couldn't help but notice this post gained a lot of traction and multiple owners having this issue, I was surprised by the fact that I wasn't the only one tbh because it was extremely difficult finding people with this specific problem. I know I'm 2 years almost late to this lmao, but I have the fix to this problem!! I figured it out awhile ago and the car has been great for almost a year now. I used to get a code that said something like "IPC Control Module No Communication". Which is indicating something wrong with the Instrument Cluster, DO NOT TRUST THAT CODE UNTIL AFTER SCANNING ALL MODULES! I took a trip to the dealership and they told me they fixed the issue the next day (all they did was replace tpms sensors lol). after starting the car the same problems persisted with the Instrument Cluster and ultimately was not fixed by the dealership, they quoted me $4400 in repairs after I just spent $2000 in repair cost on a "maybe it'll fix it". Obviously I said hell tf no and went elsewhere. I tried a few mobile mechanics and they couldn't figure out the issue themselves, I ended up learning how to fix it myself. So I learned how to use a VAG-COM based tool (in my case I used a pro plan OBDeleven but you can use VCDS if you'd like/know what you're doing.) Next, I got the car to function temporarily with the battery work around I mentioned earlier in the thread, you NEED to have the car temporarily functional using that workaround for your VAG-COM based device to respond to the car. After getting the car to eventually respond to OBDeleven, I got a series of codes that all indicated No Communication Between Modules. (Almost all modules [Brakes, Engine, Transmission, Central Electrics, Airbag, Air Conditioning, etc.] had a No Comms Code of Some Sort) After hours on hours of researching (because i was just some 17 yr old and not a mechanic or vw tech to any degree). I ended up diagnosing the issue as a bad CAN Gateway Module. Now before the next step, you are going to need to screenshot / write down all of your "GATEWAY LIST CODING" in other words your cars exact electronic hardware features, there will be a pencil icon on the obdeleven app in the control units section (they'll look like check boxes in the obdeleven app or the "CAN BUS GATEWAY" tab in VCDS) to replicate your exact gateway settings to a new or used replacement gateway module. Now come to find out, VW loves to change the spot of some modules in their cars on slightly different feature packages of the same car (Stupid I know, but necessary to VW I guess). But in my case I have a B7 2012 NMS Passat SE A32 Saloon 2.5l W/ Sunroof (yes that matters) and the gateway was located underneath the steering wheel / directly above the gas pedal, past the plastic trim cover. My gateway, to my car model in particular was a 7N0 907 530P, now if you're going to buy a replacement, beware of many various stipulations. If you're buying a new gateway from VW, I recommend calling the parts department at your local VW and running your specific VIN with them because some gateways to older vehicles have been updated to newer hardware numbers, just ask them for the part number to your car or just purchase it with them over the phone. Now if you're buying a used replacement gateway (like how I did off ebay), I recommend buying a gateway with the EXACT hardware numbers and software version your current gateway has to make things easy. *ONLY if you're skilled in retrofitting and know what you're doing, then experiment with different gateways if you'd like. [you may lose/add functionality to certain features in your car] After you have your replacement and all your coding info from your old gateway (that you screenshotted / wrote down earlier), you are going to want to unhinge your battery from the terminals and proceed to install your new gateway module. Then after install, you'll reconnect the battery and plug in your VAG-COM device to your OBD2 port again and make your way back to the "GATEWAY LIST CODING", from this point you will take all the settings that were checked on obdeleven/vcds and apply them accurately to the new gateway. (BEWARE IF YOU BOUGHT A USED GATEWAY, THERE WILL BE BOXES ALREADY CHECKED FROM THE PREVIOUS CAR IT CAME FROM, UNCHECK ALL BOXES THAT WERE NOT PREVIOUSLY CHECKED ON YOUR OLD GATEWAY) After that's all said and done, you will apply these settings and take your keys out of ignition. Let the car sit for 3 minutes or so to be safe and then turn the car back on and everything should be working again!! I would clear ALL "No Communications" Codes in each module using the obdeleven/vcds tool after you're done.
This took me a very long time to figure out myself and I'd hate to see someone struggle with the problems I had, from my belief, I'm sure the gateway had water damage to a degree or a solder joint was loose on the chipset. I disturbingly discovered the sunroof was on backwards somehow from the previous owner and the drains were clogged, so it explained the humidity problem when i had it. I bought the car used as my first vehicle and let me tell you, electrical problems can be confusing as hell if you don't know what you're doing, especially VW vehicles. I will most definitely say that I'm a diehard VW guy now that I can diagnose things and understand what certain codes mean to a degree.
Also! If you're still having problems after this with the "IPC Control Panel Lost Communication" Code after this, it may actually be a defective cluster (MAKE SURE ITS YOUR ONLY MODULE THAT LOST COMMS WITH THE VEHICLE). I cloned/replaced mine for good measure by buying a used one on ebay with the same hardware numbers and shipped it up to this place in PA to be cloned from my original. This is their website: Instrument Cluster Store | Instrument Cluster Replacement & Repair
It was like $120 for the used cluster and $300 for the cloning service. This wasn't necessary for me but as i said I did it for good measure. I could've realistically fixed my car for $230, but hey $600 ain't bad compared to $4400 on a "maybe".
I really hope me saying all this helps! Good Luck.