Odd noise after turning ignition off

I got my 2013 Passat TDI back in February at around 70k, picked her up as a CPO from the dealer. Since then she’s currently at 83k. I’ve done an oil and air filter changes, as well as tire and brake maintenance. At 80k I took her in for the DSG service at the dealer. Lately I’ve been hearing this odd ticking noise, it wasn’t making when I first bought it. I only hear it on the drivers side of the car, while in park with the engine running after driving for a period of time. Well today I drove about 45 minutes mostly freeway, get to my destination and shut the car off with little cool down time (I’m often bad about letting the car cool down a bit before turning off the engine) and heard this awful awful noise from underneath the car. Put the car in accessory mode and it immediately stopped. To note the auxiliary fan (which did kick on after turning the car off) wasn’t the problem I don’t believe. It wasn’t coming from the radiator area and the fan sounded normal.

I’m wondering if it might be at all related to my DSG failing ? Lately it’s been slipping really hard into first from a stand still, after the fluid flush at the dealer it just doesn’t seem to be working right.

It kind of sounds like something is loose in the exhaust, but that would not explain the sound going away if the ignition is turned to accessory mode. The hard shifting is worrisome. I would be tempted to return the car to the dealer and complain about this new noise and the hard shifting and lean on the CPO warranty. The hard shifting is NOT normal.

Tom in PT said:

It kind of sounds like something is loose in the exhaust, but that would not explain the sound going away if the ignition is turned to accessory mode. The hard shifting is worrisome. I would be tempted to return the car to the dealer and complain about this new noise and the hard shifting and lean on the CPO warranty. The hard shifting is NOT normal.

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Oops. I re-read what I originally posted. So I got to my destination, turned the car off (completely) that auxiliary fan kicked on and I heard that noise underneath the car. Turned the car back on (completely started the engine) the noise stopped, and then turned it off again and the aux Kicked back on but the noise was gone. Haven’t heard it since.

I’m trying to avoid taking it to the dealer until I know 100% for sure what’s wrong so they don’t charge me a diag fee. I know something is up.

For the hard shifting it’s mostly when I first start my trip. I usually remote start to let the car get to temp before leaving anywhere, but even still it happens. I’ll be at a stop light or sign and let off the brake the car takes a few seconds and then jerks forward then I push the gas. I disabled the hill hold assist too, so I know that’s not what I’m feeling.

Tom in PT said:

It kind of sounds like something is loose in the exhaust, but that would not explain the sound going away if the ignition is turned to accessory mode. The hard shifting is worrisome. I would be tempted to return the car to the dealer and complain about this new noise and the hard shifting and lean on the CPO warranty. The hard shifting is NOT normal.

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Mine does probably the same thing...after engine is hot when turned off there is a irregular cluck noise fairly loud from the exhaust pipe area. It does not happen all the time.

Mine has occasionally done this as well. I am pretty sure that it is related to the cool-down needed after a regen, as both fans are running on high after engine is turned off. Not sure if it means I interrupted one, as I do not have a VCDS.

The EGR flapper valve cycles through full range of motion each shutdown, this verifies it's fully functional each start up. it should be independent if fan are on or not.

A theory: combustion (a mini-explosion) of unburned fuel injected in exhaust in a regen cycle when fuel gets sufficient oxygen in the tailpipe.
I have never had this happen and interrupt a regen frequently.

My 2014 Passat TDI is making this same noise. Did you ever find out what was causing it?? It has only made the noise a handful of times in a month, but it worries me. Tired of throwing money at this stupid car!!

Mine still does this every now and then. I think it is the exhaust flap valve (OEM Number: 1K0253691D). I would consider swapping it with the one I just took from my son's exhaust, to see if it makes a difference, but it doesn't bother me that much -and it hasn't caused any issues so far (153k miles).