Subaru mass air flow sensor problems install#

If neither of these steps is effective, replacing a mass air flow sensor is usually a simple job.ĭiagnosing drivability issues is a process of elimination. An MAF-sensor-specific cleaner may be able to take care of any contamination.

Subaru mass air flow sensor problems install#

Blow out the intake tubing and install a new air filter to prevent future dust intrusion. If your intake system is good to go and you’re still having issues, there are several things you can try: A vacuum leak, a clogged air filter, restricted exhaust, a clogged catalytic converter or a broken intake tube can mimic a bad MAF sensor, so check the intake system to rule those issues out first.

These issues don’t always mean that your MAF sensor is faulty.

Hard Starting: Engine starting requires more fuel than idling, but the ECM may not command enough fuel injection to start the engine right away if the MAF sensor signal is skewed.

Hesitation or Surging: During acceleration or cruising, you might notice hesitation or sudden abnormal power, which can be unnerving.

This can also overload the catalytic converter.

Black Exhaust Smoke: In some cases, the ECM may err so rich that black smoke comes out of the exhaust.

If the ECM errs rich, it may add more fuel than necessary, causing poor fuel economy.

Poor Fuel Economy: The MAF sensor does not have to fail completely to affect fuel economy.

If the MAF sensor has issues, the engine may not run smoothly, especially while idling.

Rough Idle: Smooth idle is difficult to achieve without the proper amount of fuel.

Trouble Accelerating: If you’re having problems accelerating into highway traffic or while passing, the ECM may be limiting injection due to MAF sensor problems.

Illuminated Check Engine Light: Performance and circuit diagnostic trouble codes may refer directly to the MAF sensor, but fuel trim and misfire codes can also be linked to the MAF sensor.

There are several symptoms of a bad MAF sensor, and not all of them are immediately obvious: If you have a bad MAF sensor, the engine control module (ECM) cannot calculate fuel injection correctly, which can lead to larger issues with your vehicle. Acceleration might require a rich AFR, up to 12:1, while cruising requires a leaner AFR, sometimes as low as 22:1. The ideal AFR is 14.7:1 (14.7 pounds of air to 1.0 pounds of gasoline), but real-world AFR varies. Measuring air mass is critical in calculating how much fuel to add to achieve the correct air-fuel ratio (AFR). The mass air flow sensor measures the air mass flowing into the engine intake. If your vehicle is having performance issues, you may be experiencing one of the symptoms of a bad mass air flow sensor. Several sensors and actuators come into play, such as the mass air fuel (MAF) sensor and fuel injectors, and just as with any other car part, these sensors and actuators can degrade over time. Modern electronic engine controls calculate the correct quantity of fuel for a given situation.