Audi A6 AdBlue Failure Leaves Owner Stranded

Had the same DEF fluid system failure on my 2020 Audi A7 TDI. The issue was with the SCR catalyst system, specifically the connection between the AdBlue tank and dosing unit. The emissions control system detected incorrect fluid flow and triggered a complete engine lockdown as a protective measure. The repair required: Complete diagnostics scan, Removal of DEF tank assembly, Replacement of dosing valve and supply line, Replacement of corroded electrical connectors, System reset and calibration, Fresh DEF fluid fill This is considered a serious repair since it impacts the entire emissions system and can prevent engine operation entirely. The work took about 6 hours at the shop. These components are critical for maintaining fuel efficiency and meeting emission standards. Without repair, the vehicle enters a countdown mode and eventually prevents starting to protect the SCR catalyst system from damage. Worth noting that regular DEF fluid quality checks and timely top-ups can help prevent similar failures.

Thanks for sharing your experience with the DEF system repair. My Audi A6 had almost identical symptoms, and the dashboard alert showed the same emissions control warnings. The dealership also found issues with the dosing unit, but in my case the tank capacity sensor was faulty too. Did you track the total repair cost for your case? Mine needed additional work on the tank sensor assembly which wasnt initially diagnosed. Just wondering if you had any recurring issues since the fix, particularly curious if your DEF fluid consumption returned to normal levels after the repair.

Following the full system repair for 250 Euro, my DEF fluid consumption returned to normal specifications. The injection system now operates as intended, with no recurring issues in the 6 months since the fix. The main problem was indeed the faulty connection between the tank and dosing unit, which affected the SCR catalyst efficiency. The repair shop found the AdBlue tank empty warning was triggered by the defective output line, not an actual tank capacity issue like in your case. Once they replaced the connection components and performed a full system reset, the injection rate normalized and all warning lights cleared. The fuel efficiency also improved slightly after the repair, likely because the emissions system was finally operating at optimal levels. Regular DEF fluid level monitoring shows consistent consumption rates now, matching factory specifications.

Went to the dealership today for the full repair. The mechanic confirmed that my tank capacity sensor and dosing unit both needed replacement. The dashboard alert kept showing the emissions control warning until they did a complete system reset. The total repair came to 890 Euro including parts and labor. They had to order a special electronic module for the tank sensor which took an extra day. The injection system is working perfectly now and the SCR catalyst readings are back to normal. At first they only quoted for the dosing unit, but the diagnostic scan revealed the additional sensor problem. Glad I had them check everything while they had it apart. The mechanic showed me the corroded sensor unit they removed, definitely needed replacing. Just filled up with fresh DEF fluid and everything is reading correctly now. No more warning lights and the engine starts perfectly. Will monitor the fluid consumption over the next few weeks to make sure its staying consistent.