DEF Warning Light (Diesel)
The diesel exhaust fluid reservoir is low on fluid.
Diesel exhaust fluid (DEF) is an aqueous urea solution made with 32.5% urea and 67.5% deionized water. It is standardised as AUS 32 (aqueous urea solution) in ISO 22241.[3] DEF is a consumable in selective catalytic reduction (SCR) that lowers NOx concentration in the diesel exhaust emissions from diesel engines.
