In 2005, Volkswagen issued a service bulletin switching BEW-engine TDIs to 5V glow plugs (part number N10591607). It didn't hold — a follow-up bulletin (28F6/T9) reversed the change back to 7V glow plugs (N10591609), and dealer ECUs needed a corresponding reflash to match.
If your car went through the first dealer update but not the second, your ECU is still calibrated for 5V glow plugs that are no longer the correct spec. That mismatch is a common cause of cold-start hesitation, glow plug warning lights, and premature glow plug failure on affected Mk4 BEW cars.
This is a bench service, not a remote flash — we need your physical ECU. Order it, and we'll email shipping instructions for sending it to our Colorado facility. Turnaround is typically 2-3 business days once it arrives, and we ship it back the same way.
FAQ
Do I need this if my car has always had 7V glow plugs?
No. This only applies if your ECU was updated under the original 5V bulletin and hasn't received the follow-up correction.
How do I know which glow plugs are in my car?
Check the glow plug part number, or check your service history for the 2005 dealer bulletin. If you're not sure, contact us with your VIN and we can help you determine which update you need.
Is this the same as the BRM/CJAA relay update?
No — that's a different fix for a different engine and symptom. See the BRM/CJAA glow plug relay update on the related product page.
Do I ship my whole ECU or just remove it myself?
Just the ECU. We'll send removal and shipping instructions by email after you order.
