The Mass Air Flow (MAF) sensor is a highly-important part of the fuel injection system of your Mercedes. It is found in between the intake manifold and the air filter of your Mercedes engine. Its purpose is to measure the air entering the engine through the intake manifold.
Modern cars like your Mercedes will use an IAT sensor (Intake Air Temperature) to measure mass air flow. The IAT sensor can come in a variety of different forms but most cars will use a hot-wire sensor. Let’s talk about this important component a bit more and learn to identify some warning signs of failure.
Hot-wire MAF Sensors
A hot-wire MAF sensor uses an electronically-heated wire. It has a temperature sensor nearby to record temperature changes. When the engine isn’t being exerted such as when your Mercedes is idling at an intersection, only a small electrical current is needed to maintain the temperature of the wire. When you accelerate, however, air enters through the intake manifold at a greater speed and quantity, rapidly cooling the wire. This requires a greater electrical current to keep the wire hot. The more air flow, the more current necessary.
What this means is that the flow of air entering the engine is directly proportional to the current needed to maintain the wire’s temperature. This is what your Mercedes uses to quantify air flow.
The data that is collected is interpreted by an electronic chip and relayed to the engine’s computer known as the PCM. The PCM can then use this data to influence the amount of fuel that is injected into the engine. This keeps the air and fuel inside the combustion chamber perfectly balanced.
Importance of the MAF Sensor
The mass airflow sensor is important because it’s function directly impacts engine performance. As you know, your Mercedes is a high-performance vehicle, but it is also highly efficient. When the MAF sensor fails, both of these factors become compromised.
Without the exact data regarding air inside the engine, the PCM is left guessing as to how much fuel to inject. This inaccuracy cripples your engine’s performance, resulting in rough idling, bad acceleration, misfires, and stalling. Because the PCM is relying on guesswork, you’re going to waste far more fuel costing you time and money at the pumps.
Common Problems with the MAF Sensor
The sensor used within the MAF system is very delicate, as is the hot wire. Poor installation, road debris impacts, and general wear and tear can cause the sensor to become worn out or damaged. When this happens, the sensor will need to be replaced.
As it comes into direct contact with outside air, over time, the MAF sensor may become clogged or contaminated with dust and grime which can stop it from working. This can often be resolved by cleaning and reinstallation but may require complete part replacement too.
MAF Sensor Error Codes
Aside from the side effects of MAF sensor failure, the engine’s computer, the PCM, will relay the issues to your main onboard computer, the ECU (electronic control unit). The electronic control unit is able to interpret this data and send out relevant error codes, notifying the driver of this by lighting up the check engine light on the dashboard.
When the driver visits a mechanic, the issue can be swiftly diagnosed thanks to the error codes, which the technician can read with diagnostic tools. Common error codes involving the MAF sensor include:
- P0100 – Mass Air Flow Circuit Malfunction
- P0101 – Mass Air Flow Circuit Range/Performance
- P0102 – Mass Air Flow Circuit Low
- P0103 – Mass Air Flow Circuit High
- P0104 – Mass Air Flow Circuit Intermittent
- P0171 System Too Lean (Bank 1)
- P0174 System Too Lean (Bank 2)
Don’t Delay in Fixing the MAF Sensor
A faulty MAF sensor will cost you more and more money the longer you ignore it. This isn’t because replacing or repairing the part is expensive, but is instead due to the amount of fuel wastage your Mercedes will experience as a result of parts failure.
At Master Mechanics Auto Repair of Battle Creek, Portage, and Kalamazoo, MI, we know that unexpected part failure can be stressful for drivers, which is why our team of technicians is the friendliest bunch around. We’ll put you at ease and explain the problem with complete transparency, allowing you to make an informed decision on what to do next.