Another way, if you don't have an ammeter:

Remove the driver side lower dash cover
Unplug the big C104 connector.
The C104 is the one with the tail going toward the back of the car, don't confuse it with the connector for the turn signal switch which looks similar. It is easy to tell them apart because the tail of that connector goes up the steering column.

Once you have C104 apart, check between the pin side, pin 14, to ground. You should have about 2 ohms if the element is good.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech