Mitsubishi Mass Air Flow Sensor Symptoms

Mitsubishi Mass Air Flow Sensor Symptoms

It’s safe to say that without the MAF sensor, the engine won’t be able to perform properly. Together with the motor’s control unit, it determines how much fuel needs to be injected into the engine. That, in turn, is dictated by the mass flow rate of air that enters the combustion chamber. Now, it sounds a bit complicated, but the MAF sensor is, indeed, an incredibly important device.

It’s pretty reliable, too, but it doesn’t last forever. Over time, the sensor tends to wear out or go bad. So, how do you figure out that it’s malfunctioning without a mechanical degree? By learning about the most common side effects and symptoms, of course! Join me, and let’s check out the most obvious signs of a faulty Mitsubishi mass air flow sensor!

How do you inspect a Faulty MAF Sensor?

Before we check out the side effects and symptoms, it’s very important to know how to diagnose the mass airflow sensor. To locate it, pop the hood. You’ll see it sitting right between the air filter box and the intake manifold. The exact location of the sensor may vary, though, depending on your vehicle’s make, model, year, and engine design. If you still have your Mitsubishi user manual lying around, it will help pinpoint the sensor’s location.

Running a Full Scan

Running a Full Scan

Now, a new MAF sensor isn’t particularly cheap, which is why I always recommend inspecting it before buying a replacement. The good news is – it won’t take much time or effort to diagnose it. Again, you’ll find the correct measures/values in the user guide. If you don’t have it, look for it online. For running a scan, we will need an OBD-II scanner.

These are available for 30-40 dollars. There’s a catch, though: to be able to not only read, but also clear the fault codes, you’ll have to pay $100-150, or even more. So, go ahead and connect the scanner (it plugs into a port on the dashboard). With the car on idle, read the real-time MAF sensor data. You’ll see zero MPG on the display. Next, start the Mitsubishi and try again.

The values should go up on higher RMPs, and lower when you slow down. If they don’t, check the MAF cables. It would be best to run the OBD-II scanner on a different car to make sure it’s working properly. If that’s the case, then you’re dealing with a faulty MAF sensor.

Symptoms, Side Effects, and Signs

#1: The Check Engine Light Pops Up

True, this warning light comes up for dozens of reasons, but that doesn’t mean you should neglect it. The Engine Control Unit, also known as the ECU, monitors every single sensor in the vehicle, making sure everything’s running smoothly. So, whenever one of the sensors is “off”, the Check Engine light pops up. Statistically, the MAF sensor is one of the most common triggers – keep that in mind.

On modern-day cars, the CEL usually gives out fault codes that make it easier to figure out the root of the problem. But, even if the codes don’t point to the mass flow sensor, I still recommend checking on it, just in case. The light will only go away once the issue is fixed, of course.

#2: A Poor Throttle Response

A malfunctioning MAF sensor “tricks” the control unit into creating a wrong mixture of air and fuel in the combustion chamber. As a result, that hurts the throttle response, which, in turn, affects the acceleration. So, if you feel like the Mitsubishi is taking way too long to gain speed, chances are, you’re dealing with a faulty MAF sensor. Rough/jerky acceleration is another clear sign.

This usually happens when there’s too much air in the mixture, and the engine doesn’t get enough fuel. A quick note: slow acceleration can also be caused by a faulty exhaust system, a broken cold air intake, and troubles with the transmission system. However, these issues are usually accompanied by strange, clanking sounds. That happens very rarely when the MAF sensor is, indeed, to blame.

#3: Smoke Comes out of the Exhaust

Smoke Comes out of the ExhaustThis is one of the obvious symptoms of a bad MAF sensor. Depending on how wrong the air-fuel mixture calculations are, the smoke can be pretty thick. The richer the mixture (meaning the more fuel there is), the thicker it will be. As for the color, if the smoke is black, then the issue is rather serious. A grey-ish color, in turn, means the mixture isn’t that off. Or, it could be that there’s a leak in the exhaust system.

So, make sure to check what’s happening in the back once in a while. Otherwise, you’ll end up polluting the air on the road and not even know about it! I also want to mention that when the engine is running too rich for a long time, that can have a negative effect on its performance.

#4: Misfires, Rough Idle, and a Faulty Start

Do you feel like starting the engine in the morning has turned into a long and annoying “ritual”? The car doesn’t fire up from the first turn of the ignition key, and the motor is constantly struggling? That might indicate that there’s something wrong with the MAF sensor. I have to mention that misfire is mostly caused by faulty spark plugs, ignition coils, and a malfunctioning exhaust.

Still, go ahead and inspect the sensor. And remember: older cars are highly sensitive to the air-fuel balance and won’t start unless it’s perfect. You’ll feel the vehicle vibrating when there’s too much fuel. And when the air levels are over the top, the engine simply won’t start. This is one of the most common 2003 Mitsubishi Lancer bad mass air flow sensor symptoms, by the way.

#5: A Drop in Fuel Efficiency

A Drop in Fuel EfficiencyLast, but not least, a poor MPG (miles per gallon) ratio is another symptom of a faulty mass air flow sensor. So, why does fuel efficiency drop all of a sudden? Well, it’s pretty simple: as I mentioned earlier, when the MAF sensor is sending the wrong data to the ECU, the air-fuel balance gets messed up. As a result, the engine either gets less fuel (which results in inconsistent performance) or too much of it.

And when there’s more fuel than the motor needs to run, it ends up burning all the excess fuel, which, of course, drops the fuel efficiency. This is very easy to keep track of: if you know the average consumption of your Mitsubishi vehicle, all it’s gonna take to notice a decrease in efficiency is one look at the dashboard.

This is important: when the engine is “underfed” because there’s very little fuel in the mixture, that will actually improve the mileage. You shouldn’t be happy about that, though, because this can also damage the engine. As you already know, mechanics charge quite a lot for fixing the motor!


So, there you have it – the most common symptoms of a failing MAF sensor. As we learned today, when it’s not working properly, that can lead to a rather long list of issues with the engine, transmission, exhaust system, and more. Poor fuel efficiency, weak acceleration, and misfire are just some of the frustrating side effects of driving around with a malfunctioning mass air flow sensor.

My advice to you: whenever you detect one of the signs/symptoms from this guide, do your best at fixing it right there and then. If you neglect the problem(s) and do nothing, best believe that a relatively small issue will turn into one big headache in the future. Drive safely, take good care of your powertrain, and enjoy the road!

Leave a Reply

Your email address will not be published. Required fields are marked *