What does 'Fuel Fired heater disabled' (P2029) mean?

Question

Car: is 1.8 2005 C180 mercedes Petrol.
Symptom: Car firing only 3 cylinders from cold at start up.
Other Codes: P303, Cylinder 3 misfired, P0313 Misfire with low fuel.

Answer 1

Misfire number 3 cylinder, with P2029 , Check the air duct for the MAF sensor to the throttle body, there should be false air leak, mass air flow performing correctly will set a misfire condition, then disables that particular cylinder. 

  Typical MAF sensor air duct, if false air gets pass the MAF, you do set a misfire condtion.