The engine cuts randomly and won't start, P1603

[Leon 20VT4]

My car is having issues. The engine will just shut off when driving and it won't start after. It gives the P1603 code which implies the ECU is the problem. The ECU was sent in and checked out OK.

The first time it happened i gave it some throttle while driving in the snow and where the ESP usually triggers it stalled a bit and the engine started shutting down. Couldn't start. Towed the car, stored it over night, deleted the code and it started right up like normal. After some minutes of driving it happened again. The car sat over night and the next day i started it without deleting any code. I drove 50meters and it shut off again. Now it's in the workshop.

Any idea what can cause this?

Prior to this i have had the engine out, the tranny off, and i had a coolant line in the front pop off emptying the coolant. The car worked fine for some days before the problem started.

[vavJETTAw36]

P1603 is internal control module malfunction. 4 possible culprits:

1. Bad ECU
2. Bad Chip/Flash
3. Low voltage
4. Some other upstream issue.


Id check your voltage first. Make sure your alternator is charging. It should be charging between 13 and 14 volts.

If that fails, check your ECU for physical issues. Are you stock or chipped?

[Leon 20VT4]

1: ECU was checked and they found nothing wrong with it
2: The chip has been working good for over a year
3: The workshop mentioned that they measured 5V to the coils, (TFSI coils, ICM's deleted). Battery and alternator is fine.
4: Where do i start on the upstream issues?

The workshop said they have checked the main earthing points

[Leon 20VT4]

One more thing i could add; The car sat one night in the rain without the long plastic cover underneath the windscreen. Could that fuck things up?

[christianb5s4]

One more thing i could add; The car sat one night in the rain without the long plastic cover underneath the windscreen. Could that fuck things up?

Are you sure the ECU was checked out completely? If that rain guard was not in place and it rained, the ECU box is notorious for getting moisture/water in it and causing weird electrical issues.

[erykv1]

I've run no rain guard for 2 years, no issues, as long as the ecu cover is on.
Have you checked your engine harness? The wires can get brittle from all the heat and crack causing lots of issues.

[Leon 20VT4]

If i were to measure the engine harness and other wires, how should i do it? Wire to ground? Wire to wire? Are there any way to do this systematically?
Are there any sensors i should measure and how?

[vavJETTAw36]

If i were to measure the engine harness and other wires, how should i do it? Wire to ground? Wire to wire? Are there any way to do this systematically?
Are there any sensors i should measure and how?

measure continuity end (various connector) to end (ecu pin outs)