OBD2 Trouble Code P0102

OBD2 Trouble Code P0102

The P0102 code is annoying but, fortunately, doesn’t pose much risk to your engine. You’ll still want to get it fixed because it can cause various annoying issues, so we hope this guide can help you solve the problem.

What Does P0102 – “Mass Air Flow Circuit Low Voltage Input” Mean?

The mass airflow sensor (MAF) constantly measures the amount of air being sucked into the motor. The engine’s computer uses that measurement to calculate the amount of fuel to add to the cylinders in order to maintain the perfect air to fuel ratio. That’s really important for maximizing fuel efficiency, power, and engine health.

The mass airflow sensor sits in the air stream and sends DC voltage to the computer. The higher the voltage, the more air is flowing past it. If the voltage is below the normal operating range, the voltage input is low, and you get error code P0102.

How Serious Is Code P0102?

A bad MAF usually won’t harm anything but your wallet. The biggest problem is that you will get terrible gas mileage, and your car will fail inspection in states that require inspections. However, as is the case with all codes, some serious issues may occur in rare circumstances.

Stop Driving

  • If the car’s performance is suffering greatly
  • You hear unusual engine noises, especially knocking or loud clunks

Related Sensors

  • MAF
  • MAP (manifold absolute pressure sensor)
  • Knock Sensor


  • Check engine light is illuminated
  • Minor performance issues
  • Pinging
  • Fuel economy is lower than normal


There are four main causes of this code.

  1. Your air filter is dirty
  2. The MAF sensor is dirty
  3. The MAF has failed
  4. The wires or electrical connections are damaged

It’s a rare issue to have, but it is possible for the computer to have failed as well. If the PCM/ECU is having trouble interpreting a signal because it is malfunctioning, it may create a variety of fault codes.


Most of the time, the fix will be quite simple. Anyone with a few basic hand tools can replace the MAF sensor if need be, and you may not need to replace it. Follow these steps to first isolate the issue, then solve it as quickly as possible.

Locate the MAF

If you don’t have access to a service manual, you can usually find the sensor by first locating the air filter housing. Near the air filter will be wires going to a small box that is attached to the air intake tubing.

You can also usually see the sensor itself if you remove the air filter and look down the intake tube. The sensor is a small copper wire that sits in the intake. Sometimes they are in a small metal ring, sometimes they are inside a plastic box behind a flap. The electrical wires coming out of the sensor’s backside will help confirm that you’ve found the correct location.

Disconnect the Sensor and Inspect the Wires

Take a good look at the wires and connector. Faulty wiring is one of the less common causes, but it’s easy to check. Sometimes critters will chew through a wire, or heat will melt the insulation and cause a short. Look for black scoring, melted plastic, or heavy corrosion.

If you find any of those issues, replace the broken component.

Inspect the Air Filter

If your air filter is dirty, it can cause a low reading. In some cases, it is probably easier to simply replace the air filter and clear the code. If the code stays clear, you are good to go.

There is one thing of note, however. If you have a reusable oil-based filter, like a K&N or BBK filter (these are typically aftermarket parts), you don’t need to replace the filter. You just need to clean and re-oil the filter. That oil is notorious for ending up on the MAF sensor and causing this error, so if you have an oil-based filter, you’ll probably need to perform the next step as well.

Clean the Sensor

The easiest way to clean an airflow sensor is to dip a long Q-tip in high-proof alcohol or electronics cleaner and very gently dab at the copper wires. It’s very important that you don’t break those wires. Once the sensor is clean, re-assemble the airbox and clear the code. It may take an hour or so of driving around before you know whether the error will occur again.

Replace the Sensor

If you are still having the issue after cleaning the sensor, you will need to replace it. Here is a simple video that outlines the entire process. You should only need a screwdriver and a couple small wrenches in addition to the new sensor.

Clear the Code

Use your OBD2 scanner to clear the code. If the code comes back even after replacing the sensor, you may need to take the car to a mechanic with a more advanced scanner to check for PCM issues. As we said above, though, those are very rare.

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