Intermittent Electrical Fault
Posted: Tue Oct 13, 2026 7:44 am
Anyone else suffered from this problem? If yes what was the cause and fix? I am suffering this post new gateway module (with correct coding) installtion and J329 relay replacement:
The car has experienced intermittent loss of the instrument cluster and other electrical functions. It was recently returned after investigation and relay replacement, but during the subsequent 40-minute drive the fault occurred approximately four or five times.
When the fault occurs, multiple warning lights/messages appear, the instrument displays and indicator indications may stop working, and the climate control stops cooling or becomes unavailable. The engine has generally continued running. The systems may recover temporarily, sometimes following an ignition restart.
A genuine new VW CAN gateway was installed approximately five months ago, with initial coding difficulties. The main battery was replaced approximately six months ago. J329 relay has recently been replaced as part of the past 2-weeks investigation. A battery disconnection previously allowed the vehicle to restart, although the warnings remained.
Some additional 'whilst driving' information when the fault came back post collecting my car from xxxxxx garage:
During the fault, exterior indicators and automatic headlights continued working, the engine and DSG operated normally, and the aftermarket Pioneer/Apple CarPlay remained powered. The central dashboard display remained illuminated but was blank, with no gear indication or MFD information. There was no internal indicator tell-tale or clicking sound, although the exterior indicators worked.
Also - whilst driving I have my iphone plugged into the cable so that it 'recharges' and is connected to my pioneer headunit for waze and spotify via apple carplay
The car has experienced intermittent loss of the instrument cluster and other electrical functions. It was recently returned after investigation and relay replacement, but during the subsequent 40-minute drive the fault occurred approximately four or five times.
When the fault occurs, multiple warning lights/messages appear, the instrument displays and indicator indications may stop working, and the climate control stops cooling or becomes unavailable. The engine has generally continued running. The systems may recover temporarily, sometimes following an ignition restart.
A genuine new VW CAN gateway was installed approximately five months ago, with initial coding difficulties. The main battery was replaced approximately six months ago. J329 relay has recently been replaced as part of the past 2-weeks investigation. A battery disconnection previously allowed the vehicle to restart, although the warnings remained.
Some additional 'whilst driving' information when the fault came back post collecting my car from xxxxxx garage:
During the fault, exterior indicators and automatic headlights continued working, the engine and DSG operated normally, and the aftermarket Pioneer/Apple CarPlay remained powered. The central dashboard display remained illuminated but was blank, with no gear indication or MFD information. There was no internal indicator tell-tale or clicking sound, although the exterior indicators worked.
Also - whilst driving I have my iphone plugged into the cable so that it 'recharges' and is connected to my pioneer headunit for waze and spotify via apple carplay