MAF Sensor Replacement

What the MAF sensor does

The mass airflow (MAF) sensor is a plastic tunnel with a sensor inside, placed where outside air passes through the air filter into the engine. It measures how much air is coming in. The car’s computer uses that reading to work out how much fuel to add, because an engine needs a specific air-to-fuel ratio to run well.

Signs it may need replacing

• Check engine light is on
• The car is lacking power
• Fuel economy has dropped
• The car may not start

What goes wrong

A MAF sensor commonly gets dirty, especially when the air filter is dirty, and then cannot read the air correctly. Bad connectors and wiring harnesses are another frequent cause. Cleaning is sometimes an option, but only after diagnosis. Leaking vacuum hoses can set the same check engine code, so the cause needs to be confirmed.

How we approach the job

We inspect the vacuum hoses, the snorkel, and the air duct between the sensor and the intake manifold, because replacing the sensor without fixing a leak will not solve the problem. If testing shows a fault, we may also replace the electrical connector that links the sensor to the computer. Changing your air filter on schedule helps the sensor last.