Our (new to us) 2018 Outlander PHEV GT has an issue where after about 2 minutes of the vehicle being on (ACC or fully on), an error pops up on the stereo indicating "An error has occurred in the connection to the vehicle. Contact your dealer for inspection." After this, we can't change the volume at all until the car is fully powered off and powered back on. Again, we get just a couple minute to adjust volume, then it's stuck where it's at.

We contacted the dealer, since it was happening right after we bought it. We didn't notice it before buying or on the drive home, but we weren't changing volume much. They of course won't cover it, since we don't have a warranty that covers it. They diagnosed it for free and said we need to replace the stereo, but after reviewing all the symptoms, I'm skeptical that they put in a full diagnosis and I don't want to pay $1800 when it could also be the amp, sub, or wiring causing this issue.

I've seen and understand the wiring diagrams, but I'm hoping someone with more experience might be able to narrow down my diagnosis before I start disassembling the vehicle...or at least let me know the easiest part of all this to access for making test measurements.

Symptoms I've noticed:

1. Before error message pops up
   1. Volume controls work fine
   2. Sub works, but often has hums, buzzes, or clicks that sometimes goes along with other operations (for example, if the flashers are on)
   3. Speaker test from the secret menu sounds fine for all speakers
2. After error message pops up
   1. Volume won't change after this occurs.
   2. Sub stops making noise (it usually makes a thump as it shuts off)
   3. Other speakers work fine.
   4. Speaker test from the secret menu sounds fine for all speakers, except the sub, which makes no sound.
3. Radio error log indicates an error 2003 is logged

 

If you are talking about volume controls on the steering wheel (SWC): check all contacts (SWC cable to radio unit) and buttons, maybe you need to clean them. In my 2013, I've noticed that resistance (measured myself) is fluctuating when pressing and holding some buttons on the steering wheel. In my 3rd party radio (changed from OEM for good) I have a possibility to re-calibrate buttons and I do it 1-2 times per year if I'm lazy and do not want to open steering wheel panel and clean buttons. Note, high humidity and temperature variations will provoke faster oxidation of the electrical contacts, especially buttons.

If you talk about digital volume control in your radio unit it is clearly a bug. You need to update software on it
In the best case, a connection to CAN bus, or ACC or other signal is not stable and unit is confused and kicks fault code after awhile and disables volume inputs (stupid design logic). Maybe you can fix it by cleaning all contacts on the back of your radio.

PS: If I were you, I would change the whole stereo unit to a 3rd party one (1- or 2-din standard with bluetooth etc features or high end smart Android-based unit for less than $600). Mitsu's stereo units are bad by design (especially bluetooth unit behind the radio at the bottom of that space).

 

So glad to see another person post about this. My 2018 Outlander SEL with the Rockford Fosgate media system is having this identical error (down to the sub-pop when turning it on and off).

Everything works just fine for anywhere from 30 seconds to 15 minutes before the error message. Have it at the dealer right now, and they’re trying to troubleshoot it, but no word back after 4 days and I’m playing Dr. Google. *flagging this post to watch.*

 

I did some testing with a multimeter on the amp and speaker circuits the other night, since I could test them without much effort by reaching under the seat.

I’m not a car audio expert, but I found it strange that one of two sub coil circuits had +12V when the car first turns on, then 0V after it the error message. Not +12V across the coil, that had a negligible voltage difference, but both pins were +12V (with a small difference between them). The other sun circuit had something different, but around +5V. I found this odd, so I think there’s an issue with the amp. I have a replacement already and just waiting for a day to take the seat out and replace the amp. I’m hoping that’s the issue for me, but I’m not 100% sure.

 

My dealer took 4 days to “try to diagnose” the issue (code for they didn’t do anything, but focused on the things they knew how to do - oil change, rear brake job, and rotating the tires) and didn’t find the problem before I needed the car back. It’ll be another week before our schedules align for me to bring it back, so I’ll keep watching to see your progress!

 

It took a lot longer to get around to replacing the amplifier than I expected. I’ve only tested it twice, for about five minutes each, but it hasn’t given me the error message since I replaced it and the volume works normally. While I had the seat off, I added something to the two subwoofer circuits to allow me to switch it off, but I haven’t verified the subwoofer is still working. I guess that means if it’s fixed, it was either the amp or the sub and hopefully it I’ll know more in the next few days.

 

Ive done a few commutes, a trip to the airport, and a couple more drives and no issues. The sub in the back is still blown, so it seems the amplifier was the problem in my case. I’m glad I was able to fix it with a used unit for around $400 instead of the multi-thousand dollar job the dealer would have ended up doing after incorrectly replacing the stereo and not fixing it, then replacing the amplifier.