Stihl MS 650

93MS 650, MS 660
13.2 Troubleshooting Chart
Measure resistance of
heating element at
temperature = +20°C (68°F)
Check thermostatic
switch
no
Replace heating
element
Does thermostatic switch
open between + 6°C (43°F) and
above + 13°C (55°F)?
Does thermostatic switch
close between + 13°C (55°F) and
+6°C (43°F)?
Carburetor heating system
in order
Resistance
approx. 8 Ohm?
no
no
yes
yes
yes
Replace thermostatic
switch
Replace thermostatic
switch