Electrical issue. Weirdness. Brake warning.

[The Law]

From my experience an old worn out and partially damaged regulator will do this under load - stuttering etc, but at idle may be able to keep things ticking over.

Check the battery voltage with the car off, at idle, and alternator output across the battery at 2000 RPM. I would like to think your car is young enough to not have any wiring issues, but give the harnesses a look over to make sure there are no shorts to eachother or ground. Check battery terminals etc.

Not had any wet footwells or anything recently?

Funnily enough, passenger foot well was wet a week or two ago.
I poked my fingers in the drains under the battery and a ton of water came out.


Sent from my iPhone using Tapatalk

[The Law]

Just did a forum search and came up with this relating to the fault codes...
18693/P2261/008801 - Ross-Tech Wiki

/P2261/008801 - Boost Pressure Control Valve (N249): Mechanical Malfunction

Possible Causes
Boost Pressure Control Valve (N249) faulty
Wiring/Connectors from/to Boost Pressure Control Valve (N249) faulty
Possible Solutions
Check Boost Pressure Control Valve (N249)
Check Wiring/Connectors from/to Boost Pressure Control Valve (N249)
Special Notes
Visually check the N249 valve for a split diaphragm and replace the faulty component with the latest revision as per the parts management system and various TSB/TPIs which include but are not limited to:
VW TPIs 2023024 and 2016986


Sent from my iPhone using Tapatalk

[Alan02]

I wouldnt worry about that code.Now, your plenum chamber full of water is another issue! It could very well be related.

[The Law]

Plenum chamber? Is that the battery tray area?
It's dry as a bone, as is the passenger footwell too.


Sent from my iPhone using Tapatalk

[SammoVWT]

Are the drain channels blocked? The footwell gets flooded when the drain channels aren't clear and water fills up and seeps in via seals or usually via the cabin filter etc. Water drips in, finds its way to all the lowest connector sockets and causes lots of shorts etc. Can leave corrosion behind and sometimes kill off electronic modules. You might have gotten off lucky, I've only had my footwell a little wet once, because I missed my annual leaf clearing schedule one year..

[fourringsrus]

Quite often when you get the big brake warning symbol, and all your brake components (lines,fluid,discs,pads,sensors etc) are all good, the issue is that your battery is about to die.
The idea is that a braking fault warning will force you to park up and inspect the car, as you are, and seek advice,as you are, this is because many parts of the car rely on a perfect supply of electricity, lights, abs etc, this is why I would suggest a battery and charging health check might be prudent and potentially a cheapish solution

Stuart

[The Law]

Battery is brand new.
Alternator is charging as it should. Checked it with a meter to make sure it wasn't drawing power.

Out of curiosity where's the n249 boost pressure control valve??


Sent from my iPhone using Tapatalk

[SammoVWT]

What voltages are you getting on the system? Are the battery connections on properly? I would expect that valve to be somewhere near the turbo. I've had a whole bunch of electrical faults lately, mostly due to old/frayed wiring and cracked insulation, its not fun work diagnosing these issues - has the valve code come back?

I'm not sure what module you have under the footwell, just hoping you dont have any residual water behind there. I would be tempted to run the AC on cold just to dehumidify it a bit - I dont have that luxury!

P1602 power supply undervoltage - This one is what concerns me most

[The Law]

Battery connections are fine. Alternator is running 13.8 volts.
May be my imagination but the car seems to be running smoother having had the error codes erased.
None have popped up again since.


Sent from my iPhone using Tapatalk

[SammoVWT]

Voltage seems good, assuming that's at idle?

You might be lucky since it's all dried out now - just make sure your drains are clear so when we get another downpour it doesnt flood again. Its always one of those things you wish you had done in hindsight - keep an eye on it though, you will know where to start looking if you get issues again

The joy of intermittent faults!