Important Functions of Your BMW’s MAF Sensor

Posted on October 26, 2020 by Carson Wileman

Knowing the functions of a BMW’s mass airflow sensor will not only help you better understand how your car’s engine runs, but will also help you identify quickly when you’re dealing with a faulty airflow sensor.

This knowledge, along with precautionary care, will help keep your BMW’s engine running efficiently for the lifespan of your vehicle. This article will help you understand the different functions of a mass airflow sensor, the problems that can arise with a faulty sensor, and how to fix it.

Functions of a Mass Airflow Sensor

A mass airflow sensor for a BMW measures the oxygen flowing to your engine for the perfect air-to-fuel ratio. The mass airflow sensor increases the efficiency of your engine, resulting in optimized performance and enhanced fuel economy.

Modern cars use a hot-wire type of airflow sensor. A hot-wire mass airflow sensor has a small, electrically-heated wire. A temperature sensor that is installed close to the hot wire measures the temperature of the air near the hot wire. A small amount of air flows around the hot wire when the engine is idling, so it takes a low electric current to keep the wire hot.

When you hit the gas, the throttle opens, allowing more air to flow over the hot wire. The passing air cools the wire down. The more air that flows over the wire, the more electric current is needed to keep it hot.

An electronic chip installed inside the airflow sensor translates the electric current into a digital signal and sends it to the engine computer, also known as a PCM. The PCM uses the airflow signal to calculate how much fuel to inject. This calculation helps keep the air to fuel ratio at the optimal level. The PCM also uses the airflow readings to determine the shift points of the automatic transmission.

Warning Signs of Mass Airflow Sensor Failure

Unfortunately, mass airflow sensor failure is a common problem with BMW’s. The first sign of a problem is the check engine light illuminating on your dashboard. However, here are some other warning signs to watch for:

Rough Running or Idling

This problem occurs when too much air is sourced by the engine and the air-to-fuel ratio is imbalanced. Due to the abundance of airflow, the combustion process does not take place properly, causing your car to idle roughly or cause the engine to die. In some cases, the engine may not turn over at all when attempting to start your vehicle.

Difficulty Starting the Engine

If you experience difficulty starting your vehicle, it may be due to a bad mixture of air and fuel.

Difficulty Accelerating

If you notice a delay or difficulty accelerating, it could be because there is a lack of gasoline reaching the engine.

Excessive Fuel Consumption

A faulty mass airflow sensor gives an incorrect reading to your engine’s computer, causing the engine to consume too much gasoline.

Engine Dragging

If you notice your engine dragging when carrying extra load in your vehicle, it may be due to a faulty mass airflow sensor. Carrying extra weight requires your vehicle to use more gas to run efficiently, and with a faulty sensor, your vehicle cannot calculate the right ratio of air-to-fuel needed to run properly.

Causes of Mass Airflow Sensor Failure in Your BMW

While BMW’s are known for quality, they fall victim to mass airflow sensor failure. The leading cause of faulty sensors is from environmental wear-and-tear over time. The sensor eventually gets dirty and needs to be cleaned or replaced altogether.

Knowing the warning signs of mass airflow sensor failure and taking preventative care measures can help put a stop to a problem before it starts. When left unattended, an airflow sensor failure can escalate into further, more chronic problems with your vehicle’s engine.

Keith Cox Autobahn Can Help

At Keith Cox Autobahn in Bellingham, WA, we are specialists in foreign brands like your BMW. Over the years, we’ve built trust with our customers and are here to serve you in all your auto service and repair needs.

Give us a call when you experience a faulty airflow sensor or have any other concerns with your BMW, and we’ll schedule an appointment and take care of the rest. We’ll have your car back on the road in optimal health quickly so you can drive with confidence.