MK3 Intermittent Non-Start Issue

[turbostu]

Hi all - I've been lurking as a guest using the search function on here for the past couple of months, decided to register to hopefully ask a couple of questions as I'm stumped with this intermittent issue I'm currently having.

I bought a used 2016 MK3 Leon in February this year, all seemed OK until June - Car drives fine, however the car has now done this 5 times and I'm unable to narrow down the issue to find out what's causing it to then fix it.

After a short drive, maybe 10 miles, all fine. Unlocked car, noticed that the centre section on the cluster didn't light up to show the drivers door was open, went to start the car and nothing, no crank. Assumed it was battery related so metered the battery and was getting 12.4, so replaced the battery for new EFB type. All fine afterwards for about 3 weeks.

However, it has done the same thing a further 5 times now, twice I've had to be recovered home from driving sometimes only a few miles, sometimes I've driven 100+ miles and afterwards the car will not start. Previous ways to get the car to start would have been to disconnect the battery for 30 minutes, reconnect and it would start (the giveaway being that the IPC shows when unlocking the car, so I know it'll start)

What I've noticed is that the IPC never goes off when driving, it's only after I have driven the car, stopped, locked it then unlock it to use the car again. Tried using the 2nd key, but no change in behaviour.

Fault code from ODB2 scanner that shows when it won't start is and other noticeable issues when it happens
- U015500 - Lost comms with IPC control module
- U106600 - Radio, no communication
- It shows an park pilot error on the infotainment screen briefly, then disapears
- No sound from hazard lights or indicators
- Everything else on the car seems to work, radio, windows it just will not crank

I'm looking to take it to a local garage to see if they can investigate, as I've lost faith in driving the car any distance as the fault seems to just happen out of no where, I've tried driving without using cruise control, radio off all journey, thought was it heat related so put a sun visor in when not using it, not washed the car as thought it could be water ingress etc - Sounds silly I know!

 

[SuperV8]

some notes on U0155 here:

28827/U0155/049493 - Ross-Tech Wiki

Suggest it could be related to your CAN system so would suggest an auto electrician would be needed

 

[BillyCool]

I've just done a quick AI search and these are what it says about U0155 and IPC related issues:

Common Causes

• • A weak or dying 12V battery causing network voltage drops.
  • Loose, dirty, or corroded wiring connectors behind the dash.
  • A blown dashboard or meter fuse.
  • Physical break or short in the CAN bus data wiring.
  • Internal failure of the instrument cluster module.

How to Fix It

• • Test your car battery and clean the battery terminals.
  • Check and replace any blown fuses for the instrument cluster.
  • Unplug, inspect, and clean the wiring harness plug behind the dashboard.
  • Clear error codes with an OBD2 scanner and retest.
  • Replace the instrument cluster if the internal hardware is broken.
    
    As @SuperV8 said, an autoelectrician is probably your first port of call.
    
    
    

 

[MarkDH]

Is the battery being charged by the alternator?

 

[turbostu]

Hi - It's booked in next week at a garage. Was just hoping that someone else may have come across a similar issue prior to then start troubleshooting myself, the garage did mention that from what I've described and past history on other VAG cars they've seen, that it could be a cluster related issue.

Battery is being charged, all good and the battery is only 3 months old.

Will update on here once they've found and resolved the problem