What happens if the DEF runs low during vehicle operation?
A) The engine is immediately shut down.
B) The vehicle enters progressive trim back modes.
C) Nothing.
D) A code is logged in the PCM to notify technicians the next time vehicle is serviced.

Question

Quizplus · Accepted Answer

If the DEF runs low during vehicle operation, the vehicle enters progressive trim back modes, reducing engine power and ultimately limiting the vehicle's speed to prevent damage to the engine. This is to encourage the driver to add DEF as soon as possible to avoid further damage.
Therefore, option B is the best choice.

What Happens If the DEF Runs Low During Vehicle Operation