2012 passat CC R line - dying while driving or shortly after start up


#1

Hey everyone, Looking for some help with my 2012 passat cc r line. Engine is dying out while driving then when try to start it back up it doesn’t work until the 5-10 try.

Took it to VW dealership they aren’t sure what it is because no codes are coming up when being scanned. they did say that they found Corrosion on the negative batter wire. could a faulty negative wire cause an engine to just turn off while driving. all electrical stuff still works at all times even when the engine dies.

My first thought was fuel pump but they said the scan would have picked that up if that was the case. also a few times after starting the car it has died shortly after starting while idling. cheers!


#2

So what engine is in the car? Gas? Turbo? Diesel? Transmission? Mileage on the engine? Do you hear a popping noise when you try and restart?

Intermittent problems are the hardest to find. What you describe could fit a number of problems. Fuel pump, crankshaft position sensor, or camshaft position sensor are 3 that come to mind that tend to act like this. You’ve already had the trained dealer mechanics look at the car with no result. It is a 5 year old car, why not have an independent VW specialist take a look at it?

At some point, the car will no longer restart. At that point the answer will be easier to find.


#3

Did they fix the battery cable? And take off the cables and check each end for corrosion at the connection?


#4

2LT, premium gas always,automatic, 89k km, no popping noise usually starts up perfect and can drive it fine but recently its died once a day while driving. thanks for your information. i think i’ll take your advice and go to a VW specialist.


#5

The engine stalling might be caused by a defective Crankshaft Position sensor.

https://www.rockauto.com/en/moreinfo.php?pk=2413666&cc=1502723&jsn=384&jsn=384

One of the functions of the crank sensor is to inform the computer whether or not the engine is rotating.

If the computer looses the signal from this sensor, and no longer senses that the engine is rotating, the computer see’s no reason to operate the ignition and fuel systems, and the engine shuts down.

And no, a faulty crank senor doesn’t always turn on the Check Engine light.

Tester


#6

And yes, this could be caused by a bad connection on the negative,( ground ) side.

Grund problems are funny, sometimes they will let small amounts of current through, like your dash lights and fail when you call for more current , like your starter.
Other times I have seen them not let current to the started unless you first turn on something like the headlights and then you get juice to the starter.

You can try to see if it is a bad ground yourself.

Remove both ends of the negative cable and clean the connections. A terminal cleaner is only a few bucks.

While you have the cable out, bend it in several places. If you feel wires breaking inside, buy a new cable. If not replace the cable clean and tight ans see if it fixes the problem.


#7

The crankshaft position sensor would be my first guess & should be considered a key suspect, as mentioned by Tester above. That part can be heat sensitive, which could explain why it eventually starts after trying 10 times. That’s enough time for the engine to cool off a little. The way to confirm that, when it won’t start up after stalling, check for visible spark during cranking. One way to do that is using a spare spark plug you keep in the trunk. No spark means there’s a very good chance the problem is the sensor.

Battery & battery connections problems can cause this symptom too. When it stalls and won’t crank, turn on the headlights to bright. Do they seem to be as bright as they usually are? It would be common sense to test the battery and clean the connections in any event, replace anything associated with the battery that’s corroded. Even if that’s not the cause of the stalling, you need to have a known good battery and connections if you expect a reliable car.

When you say it stalls when driving, does it do this as highway speed? Or does it only do it when you come to a stop sign or stop light?