Sorry to go off piste, but the VAG/Seat forums that Ive looked at don't seem very good at sorting technical issues and posts seem infrequent compared to here, so I'm asking a favour by seeking advice from your good selves.

My son has come to me with a problem with his 2010 Seat Leon Mk2 FR (diesel). It has done 68K miles and has been regularly serviced. Its low mileage has accumulated mainly through infrequent long journeys. It has had an unblemished past until recently when it began to display odd electrical faults. However, the engine starts and drives as per normal. There is no MIL alarm.
I have scanned the OBD2 with Torque Pro and there are no DTC fault codes showing.
The battery was new last year and that predates the current issues. I've checked the battery voltage, connections and properly cleaned all the earth connections that I could see in the engine bay.

These are the faults with seem to occur randomly and for variable periods but appear to be occurring more frequently:
1) Alarm indicating Driver assist defective, ie cruise control is not working work.
2) Indicator lights "click" doesn't keep regular time.
3) Occasional "Brake fault: Workshop" alarm that disappears after a couple of seconds.
4) TCS alarm.
5) Coolant temperature gauge drops to zero, then back up to normal again.
6) Media centre lighting randomly increases brightness and then returns to normal.
7) Reversing sensors beep when nothing is in range to trigger them.
8 ) Reversing lights flicker or fail to illuminate when reverse is selected.

I haven't a clue what's going on here. But could this be a voltage regulation problem?

FWIW my son's local garage (a Seat dealer) wanted £160 for a diagnostic scan as a start. But as I can see no DTC codes I'm not sure that will be much help. Jules

Last edited by jules on 20th May 2022 1:02 pm. Edited 1 time in total

Are you sure his car isn’t a Land Rover

I would have thought loose connection somewhere or perhaps chewed wiring. have you tried a hard battery reset

Did not VW have problems with fuse boxes in the dash getting high impedance circuits due to internal cracking, though can't remember the years covered. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

I Like Chips wrote:

I would have thought loose connection somewhere or perhaps chewed wiring. have you tried a hard battery reset

Dartman the one wrote:

Did not VW have problems with fuse boxes in the dash getting high impedance circuits due to internal cracking, though can't remember the years covered.

SYFL2 wrote:

Are you sure his car isn’t a Land Rover

If only - I could probably have fixed that.  Jules

My son found an independent VAG auto-electrician in Norwich. Turns out the "Gateway module" had failed and was replaced - solving all the issues.
Took a fair bit of coding to get the new module working correctly with the car's various devices. . Apparently newer cars are much easier configure. Jules