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Full name Mass Air Flow Sensor, it’s more commonly known as a MAF sensor, air meter or sometimes simply MAF. While it might have many names, it’s responsible for just one, but still very important job: measuring the amount of air entering the engine. The ECU or PCM then uses
this information to calculate the correct amount of fuel needed for an optimal air-fuel ratio. Of course, without this information the ECU will not be able to accurately control fuel injection, resulting in an engine that will either idle roughly or worse case, not at all. Since a number of other parts i.e. faulty spark plugs, wires, injectors, etc, may mirror these symptoms, MAF sensor failure can be difficult to diagnose. However, with some expert advice from OE manufacture Delphi
Technologies, you’ll know what causes it, what to look out for, and crucially, how to replace it when it fails. Installed in the intake pipe between the air filter housing and the intake manifold, most MAF sensors work on the hot wire principle. Put simply, a MAF has two sensing wires. One is heated by an electrical current, the other is not. As air flows across the
heated wire, it cools down. When the temperature difference between the two sensing wires changes, the MAF sensor automatically increases or decreases the current to the heated wire to compensate. The current is then changed to a frequency or a voltage that is sent to the ECU and interpreted as air flow. The quantity of air entering the engine is adjusted accordingly. Why do MAF sensors fail?Since the MAF sensor is responsible for measuring air flow into the engine, they have a lot of air passing through them. In fact, more than 9000 liters of air can flow through the engine for every liter of fuel used. That’s a lot of air! And with that comes the potential for a lot of contamination. Dust, dirt and other debris can all get into the sensor and are one of the primary causes of MAF failure. Such contamination could occur as early as 18,000-25,000 miles, depending on the vehicle model. On small or compact cars, for example, the MAF sensor can clog quicker, as it is situated in a smaller engine bay subjected to more risk in critical areas (oil vapor flows and combustion debris). In this case, a replacement becomes the equivalent of a long drain oil service… it almost becomes a service-style repair. Other common failure problems include:
What to look out for in a failing MAF sensor?When a MAF sensor fails, the engine will not know the right amount of fuel to add, causing several common signs:
Troubleshooting a MAF sensorTo identify the source of any MAF sensor faults, consider the following steps:
Common fault codesCommon fault codes and causes include:
How to replace a faulty MAF sensor?Once you’ve identified that the MAF sensor may be at fault, it’s best practice to follow these simple steps:
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modest... Nearest Service & Diesel CentresWhat are the symptoms of a mass air flow sensor?Here are some of the most common symptoms of a faulty mass airflow sensor:. The engine is very hard to start or turn over.. The engine stalls shortly after starting.. The engine hesitates or drags while under load or idle.. Hesitation and jerking during acceleration.. The engine hiccups.. Excessively rich or lean idling.. What happens when your air flow sensor goes out?A contaminated or failed mass air flow sensor cannot measure the amount of air flow correctly. This causes the engine computer to miscalculate the amount of injected fuel, causing additional damage to your engine.
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