Mk6 Electrical issues

[Baldyboy83]

I have a 2010 MK6 GTI which is having some electrical issues it’s gone from flat battery to running to non starting and the ecu was unreadable by vw’s own diagnostic software however the next day it started and could be ready via Obd. Yesterday was driven for an hour and half on a longish drive & when I got home turned it off. But now the car won’t recognise the keys or even turn over. I was just wondering if anybody here had any advice as to what to look for before I spend ££££ on an auto electricia.

[Nino]

Honestly, that doesn't sound like anything that is consdered what would be a common fault lots of us have encountered.

It's hard to say over the internet but you clearly have a bad electrial issue.

if it was me, this is what I would check before calling out an auto elec. It could verywell be a failing battery or even just poor connections. This is the first thing to rule out, even if it seems obvious.

Weak battery can cause:
- ECU communication failures
- Immobiliser/key recognition issues
- Random “dead car” symptoms

Grab a voltage meter, Battery voltage (should be ~12.6V off, ~14+V running) check the terminal tightness, corrosion on terminals or ground points.

You could even have a bad/loose ground. Check Battery-to-chassis ground & Engine ground strap if you find any corrosion, rub it down.

[JSYGTI]

I certainly don’t know the answer, but have you had the battery tested?

A while ago, my GTI was having trouble starting occasionally, got the battery tested, and it was confirmed dead, just wasn’t holding charge.

That would be my starting point, but I’m sure much more knowledgeable people will chime in.

Good luck.

[Snoopy]

No communication or sporadic communication with engine ECU, and intermittent start issues is often the relay in the fuse box under the bonnet. I've had to replace a few over the years on people's VWs. It's a known issue.
The two relays under the bonnet are the same. One does power to engine ECU and the other does emission stuff. Try switching them over and see if this fixes the start issue. A new ones about £12 on ebay.
The relays have 100 wrote on the top and are part number 7M0  951 253 A

Edit: last one we bought were Bosch equivalents.
Bosch 0986332001 Relay
from a company called Parts In Motion from there own website as was cheaper than their ebay shop
£9.91 delivered.