Generac — Refilling DEF Tank
Maintenance
From a Generac owner's manual covering: MDG150, MDG175, MDG250. Check it applies to your exact model before use.
Applies to: Generac MDG150, Generac MDG175, Generac MDG250, John Deere 6068HFG05 / 6068HFG06 engine
Before you start
- Risk of poisoning. Do not ingest diesel exhaust fluid.
- Immediately clean any surfaces with water that come in contact with diesel exhaust fluid.
- If DEF is filled into engine fuel tank, do not operate engine until system is purged.
Procedure
- Verify DEF tank cap area is free of debris before removing cap.
- Wipe clean with a lint free cloth.
- Seal DEF containers between use to prevent contamination and evaporation.
- Avoid splashing DEF and contact with skin, eyes, or mouth.
- Check DEF level daily and refill tank as needed; fill port has blue cap with DEF symbol.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Correct DEF concentration: 31.8–33.2% urea
Full service-parts list: Generac MDG150 →, Generac MDG175 →, Generac MDG250 →, John Deere 6068HFG05 / 6068HFG06 engine →
Source: Generac owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.