2012 Jetta Sportwagen glow plug light and check engine light for split second


New member
Dec 4, 2020
2001 VW Jetta Tdi
So I’ve been having an issue with my 2012 CJAA where the car will loose a bunch of power then the glow plug light and check engine will turn on and off in a split second. If the car is idling it will bog and shut off. When driving it will jolt and seem to be in a limp mode for like 10 seconds then go back to normal. I can hear relays clicking under the dash so I pulled the panel off and found the bottom left two smaller relays(646) would click off and right back on. Replaced the relays and didn’t change a thing, still does it. Does anyone know what these relays are for, couldn’t find a diagram for a sportwagen. Doesn’t throw any codes, just comes on and goes right away. Very random. Anyone have any ideas?


Veteran Member
Sep 18, 2022
North Carolina
2013 & 2014 Jetta sportwagon
With VAG running, you should be able to catch the codes when it happens. Very unusual not to have any pending codes.