I'm having a P0104 error code, but there's no MAF sensor in my car (Focus mk2). There is a MAP sensor in it, but that should have another error code.
Any idea how this is possible ?
Your vehicle has a MAF sensor. Most modern vehicles with fuel injection do. The location of the MAP sensor is the intake manifold whereas the MAF sensor is usually located just before the air filter assembly. They measure 2 different parameters.
The Manifold Absolute Pressure (MAP) sensor is used by the Powertrain Control Module (PCM) for engine load input. The PCM uses this input, as well as others, to calculate the correct amount of fuel to inject into the cylinders. The MAP sensor measures the absolute pressure inside the intake manifold of the engine
A mass (air) flow sensor (MAF) is used to find out the mass flow rate of air entering a fuel-injected internal combustion engine. If I remember correctly this sensor is a hot platinum wire sensor with a thermistor to measure the heat of the element. As the air goes by it it cools the element and the amount of current required to maintain the temperature is proportional to the amount of air flow.
The element in the MAF sensor is probably dirty and needs to be cleaned using a sensor cleaner or disc brake cleaner which leaves no residue.
Here is a guy cleaning the MAF sensor on a 2012 ford focus