Refill AdBlue

Reviewed by the Service Reset editor · Updated September 26, 2026 · How we verify

These instructions apply to the Volkswagen Transporter T6 (SG) 2015-2019.
For other models, please choose your vehicle here.

The diesel Transporter T6 uses AdBlue to clean its exhaust, and when the tank runs low the van warns you with a range countdown. Ignore it and the engine will not restart once it empties, so topping up is a job worth doing yourself.

Refill AdBlue on the T6

VW Transporter T6 AdBlue filler with blue cap next to the diesel filler behind the fuel flap
The AdBlue filler (arrowed) is under the blue cap, beside the black diesel cap behind the fuel flap. Top up here, never in the diesel filler (LHD van shown).
  1. Buy AdBlue to ISO 22241 (also sold as DEF). A bottle with a screw-on spout, or the pump at a fuel station, makes it far cleaner than an open funnel.
  2. With the engine off, open the fuel flap. The AdBlue filler sits next to the diesel filler and has a blue cap — unscrew it.
  3. Pour the AdBlue in steadily. Add at least a few litres — a tiny splash may not be enough for the system to register a refill and clear the warning.
  4. Stop when the neck backs up or the auto-spout clicks off; do not overfill, and wipe any spills with water (AdBlue leaves white crystals).
  5. Refit the blue cap firmly and close the flap.
  6. Turn the ignition on and drive. The warning clears once the system has read the new level — this can take a short drive rather than happening instantly.

Never put AdBlue in the diesel tank or diesel in the AdBlue tank. The blue cap and narrower neck are designed to stop a diesel nozzle fitting, but always double-check which filler you are using.

Frequently asked questions

How much AdBlue does the T6 hold?

Around 13 litres on most T6 vans, giving several thousand miles between top-ups. Add several litres when you refill so the warning clears and you are not back at the flap next week.

The van won’t start and shows an AdBlue message — now what?

Once the tank is empty the law requires the engine not to restart. Add several litres of AdBlue, switch the ignition on and wait a couple of minutes; it should then start. If it still refuses, the level sensor may need a scan tool to reset.

Can I use any AdBlue brand?

Yes, as long as it meets ISO 22241. The fluid itself is a standardised urea solution — brand does not matter, but cleanliness and the right spec do.

If an emissions or AdBlue fault code is stored, you can look it up on autodtcs.com.

Independent guide — not affiliated with Volkswagen. Always follow your official service manual and safety precautions. Read our full disclaimer.

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