when I start the engine on the morning...

[mercedesalbania]

Hello,
I have a c class 200 cdi (w203), a year ago when I bought the car is good and when I start the engine every morning I wait for 4 min to heat the motor.
The dashboard say that From Start you have 4 min ---- 10 l/km, That is OK
But now I see that when I start 1 min ---- 12 l/km, and more...
I make a search and didn't find about this cause.
Note: Before 5 month I replace the AIR MASS SENSOR kind Pierburg.

 

[V6Matty]

sounds like your thermostat is starting to fail, meaning the thermostat is stuck open and car not getting up to temperature as normal. also the colder weather will make a difference to heat up time.

 

[M80]

But what does it read at 4 minutes ?
Is the outside temperature colder than previous ?

If the thermostat is failing the car will struggle to get to and maintain the expected 85 degrees.

 

[Rappey69]

How can you possibly use cold idling to establish your fuel useage?
why do you let a cold engine sit idling for so long?
Start it and gently drive it ! once warm then compare your fuel usage.