Wiring problems
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Speakers not working 
Solved
Volkswagen Passat 2012 TDI SE 188000 miles
I just bought a 2012 VW Passat TDI SE and the previous owner put in an android head unit and something might be wired wrong or something. None of the speakers are working, only the two tiny ones up by the windshield work. Can I have some help please. I uploaded images I think that might help
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CommentPossible Failing Alternator?? Solved
Volkswagen Passat 2012 TDI SE 192000 miles
I have a 2012 VW Passat TDi SE that I have owned since April 2025. I put in a brand-new battery when I bought it, and it lasted me all summer into august as I was starting and driving it almost every other day. In September my battery died and had to get it replaced. At that time, I thought that I had some sort of parasitic power draw specifically from my new radio I got. In late august I bought an RCD360 radio to add CarPlay/Android Auto to my car.
When I replaced my battery, I went ahead and just manually wired the power input for the radio to 12v ACC so that the radio will not receive pow… Read complete
1 report
Hey there, so the problem you're describing COULD indicate a problem with the Alternator. Since you have already fixed the issue with your radio -> it now being on only when the ignition is turned on. The new Radio wont be the problem.
Since you measured aroung 13V-13.2V (Which is a little bit lower than you want it to be) I'd suggest doing this:
Measure these directly on the +/- of the battery.
Let it idle, but turn on all Loads (AC, Heated seating, Windshield, Radio, basically everything that buts a load on the battery/alternator electically)
When you measure, you should not drop below 13.5V and not above 15V
Also try measuring with midrange RPM, also should'nt drop below 13.5V and 15V.
If you see it below 13.5 you should also, before settling on the alternator, measure the Resistance on the Cables that go from the alternator to the battery. If you see a high resistance it could also be corrosion taking place here.
Note: Please disconnect the battery when measuring the resistance in the cable. It should still work but to be 100% sure do it, since the multimeter sends its own current through the cable that could alter the result.
I hope it helps :)
Since you measured aroung 13V-13.2V (Which is a little bit lower than you want it to be) I'd suggest doing this:
Measure these directly on the +/- of the battery.
Let it idle, but turn on all Loads (AC, Heated seating, Windshield, Radio, basically everything that buts a load on the battery/alternator electically)
When you measure, you should not drop below 13.5V and not above 15V
Also try measuring with midrange RPM, also should'nt drop below 13.5V and 15V.
If you see it below 13.5 you should also, before settling on the alternator, measure the Resistance on the Cables that go from the alternator to the battery. If you see a high resistance it could also be corrosion taking place here.
Note: Please disconnect the battery when measuring the resistance in the cable. It should still work but to be 100% sure do it, since the multimeter sends its own current through the cable that could alter the result.
I hope it helps :)
Best answer (according to Aaron)
It ended up being a bad ground wire. It was the one that connects the transmission motor mount to the chassis.
CommentBattery Drain issue. Solved
Volkswagen Passat 2012 TDI SE 192000 miles
I bought an RCD360 Pro 2 off of eBay for my 2012 VW Passat TDI se and I just had to replace my battery for the second time, once back in September and once today. It has a mqb to pq plug adapter and I'm trying to figure out the best way to prevent this radio from draining my battery. I actually did end up splicing to voltage wire to the radio and connecting to the voltage wire for on of the 12v sockets back when I first replaced the battery, but apparently that didn't do the trick, which I find puzzling. I added some pictures of the eBay listing and the plug type of the radio and my car. I've done some research and it seems like some canbus adapter/converter would be the fix, but I'm not sure where to find a correct one or if that would even work at all.
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2 replies
I have owned my Passat since April 2025. I put in a brand-new battery when I bought it, and it lasted me all summer into august as I was starting and driving it almost every other day. In September my battery died and had to get it replaced. At that time, I thought that I had some sort of parasitic power draw specifically from my new radio I got. In late august I bought an RCD360 radio to add CarPlay/Android Auto to my car.
When I replaced my battery, I went ahead and just manually wired the power input for the radio to 12v ACC so that the radio will not receive power unless the key is in the ignition. I thought that fixed it because I had no issues with it from September to December. Mind you I am a first-year college student, so I really only drove it to go places during the weekends. Then when I drove home for winter break, I still started and ran it about once a week, until the battery died on me again.
Now I will say that there were signs of either the battery or starter failing because maybe sometime November it started to start rough and a little sluggish. I don't think it's the starter because when we put in a new battery for the second time it started no issues, no lag, no nothing. And this new battery was put in end of December. And it's already starting to be sluggish and rough when leaving it for a few days. I've pretty much started it every other to every other two days now since I got back to college on the 11th of January. I think the cold weather might be contributing to that a little bit, but I'm still skeptical.
This past week, I did some power draw testing where I put my multimeter in-line with the negative terminal of my battery and my car. After connecting it, I got an initial reading of around 1 amp after just opening and closing the door and after about 2 minuets it dropped off to 0.8 amps, then down to 0.5 amps, then to 0.1 amps, and after a total of around 5 to 10 minutes my multimeter settled at around 0.01 amps of power draw. And I also re-did the test with all the doors already closed and the car locked and ended at the same 0.01 amps of power draw.
I also did some voltage testing as well, where I tested the voltage of the battery before starting, which was around 12.5v. After starting it and letting it run idle for a good minute, I remeasured the voltage and that highest that I was able to get was 13.2v, I also tested it a couple times before as well and I've gotten readings of 13.05v, 13v, 13.15v. So, it's been fluctuating over the past week and a half between 13v and 13.2v. If anyone as any idea if this is my alternator starting to fail or if it's something else, I will be glad to have your input. Any and all help and suggestions will be helpful as well.
When I replaced my battery, I went ahead and just manually wired the power input for the radio to 12v ACC so that the radio will not receive power unless the key is in the ignition. I thought that fixed it because I had no issues with it from September to December. Mind you I am a first-year college student, so I really only drove it to go places during the weekends. Then when I drove home for winter break, I still started and ran it about once a week, until the battery died on me again.
Now I will say that there were signs of either the battery or starter failing because maybe sometime November it started to start rough and a little sluggish. I don't think it's the starter because when we put in a new battery for the second time it started no issues, no lag, no nothing. And this new battery was put in end of December. And it's already starting to be sluggish and rough when leaving it for a few days. I've pretty much started it every other to every other two days now since I got back to college on the 11th of January. I think the cold weather might be contributing to that a little bit, but I'm still skeptical.
This past week, I did some power draw testing where I put my multimeter in-line with the negative terminal of my battery and my car. After connecting it, I got an initial reading of around 1 amp after just opening and closing the door and after about 2 minuets it dropped off to 0.8 amps, then down to 0.5 amps, then to 0.1 amps, and after a total of around 5 to 10 minutes my multimeter settled at around 0.01 amps of power draw. And I also re-did the test with all the doors already closed and the car locked and ended at the same 0.01 amps of power draw.
I also did some voltage testing as well, where I tested the voltage of the battery before starting, which was around 12.5v. After starting it and letting it run idle for a good minute, I remeasured the voltage and that highest that I was able to get was 13.2v, I also tested it a couple times before as well and I've gotten readings of 13.05v, 13v, 13.15v. So, it's been fluctuating over the past week and a half between 13v and 13.2v. If anyone as any idea if this is my alternator starting to fail or if it's something else, I will be glad to have your input. Any and all help and suggestions will be helpful as well.
Best answer (according to Aaron)
Failing Alternator is the cause. Will see if it fixes my issue when I replace it.
CommentNo Crank No Start
Volkswagen Passat 2015 TDI SE 2.0 72000 miles
I drove over a cone back in October 2024 and it cut the nox sensor wire harness and ground wire harness which runs next to it. The car still drove fine after without issue. It wasn't until I spliced the wires back together that the car will not crank or start.
I replaced the battery and still nothing. I tested all the fuses and relays, all good.
I have no clue what the problem is. The codes it has are:
P048E
Permanent
Exhaust Pressure Control Valve 'A' Position Sensor/Switch Circuit High
P229E
Permanent
NOx Sensor Circuit Bank 1 Sensor 2
C0300
Permanent
Check report for des… Read complete
1 report
Sorry to say but it sounds like you potentially spliced the wires incorrectly or shorted them
Pilotovarela from United States 9 months ago
Tengo un golf tdi 2016 y hace poco encendió el check con el código P048E pero solo quiero saber si con cambiarlo es mas que suficiente
Comment01617 code does anyone know what this means?
Volkswagen Passat 2009 Passat cc 125000 miles
My car keeps getting a coil light coming on an going into limp mode while I'm on the motorway I keep getting a 01617 code coming up been told that the wiring mite be messed up any ideas?
16 reports
Very late to this but for me the problem ended up being a blocked DPF filter.
CommentIntermittent No Start / Rough Start and or crank
Volkswagen Passat 2012 TDI SE 194000 miles
Have a 2012 VW Passat TDI SE with 194k miles on it. I just ran into another issue with it not wanting to start with the DPF light and flashing glow plug light only on while turning over the engine. When it does want to start after 5 or 6 tries, the lights go away. And sometimes it will start and then immediately die, or it will start and drive with no issues, or it will not start at all and just keep turning over.
Some more info on this car, I do have a power draw coming from the newly replaced remanufactured alternator (about 0.6 amps) so I have to unplug the battery every time I park it. I… Read complete
Idling - vaccum problem
Volkswagen Passat 1996 Sedan 260000 miles
The car is running very rough, idling at working rpm, does not matter hot ir cold. Stalls sometimes at traffic light. Oil found in the air intake. Pcv valve was replaced but did not solve the problem. Vaccum hose was found cracked, replaced, and it did run good for a while, but not for long. Then the plastic was found cracked at air intake, also replaced but still the same problem. Diagnostics are showing only the consequences of this problem but not the solution. It is burning lots of oil, needs to be reffiled every 150-200 KM so thats almost everyday. My next step would be removing lots of other hidden hoses (that requires lots of tearing down) for inspection, checking the sensors, wires, ground, fuses. Unless somebody had this problem and know what would be the solution.
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Airbag light staying on after reseting it
Volkswagen Passat 2013 Estate 93000 miles
I had airbag light come on so reset it was ok for a day or 2 then it came back on was told could be the wires under the seat any idears please
2 reports
Radio quit working when does sunroof does not roll down
Volkswagen Passat 2009 Wagon Turbo 141596 miles
I was hooking up an amp and accidentally crossed the wire and something went wrong and everything quit the windows won't roll down the front window passenger window my sunroof quit working and my radio blew up
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Thank you!
Edit: maybe the previous owner added some extra cable it looks like. The main connection from
The android radio is the big one right next to the red fuse