Reset error code for Mass Air Flow Sensor
 

My city’s air quality test failed my car for an error code on the Mass Air Flow Sensor. I have bought and installed a new one, but how do I reset the error code so I can pass the test?

It would help if you mentioned what car you own, but I will give it a shot anyway. The code should clear itself once the condition is corrected. I would give it a few miles. If your car is 1996 or newer you can clear it with an obd2 code reader or find someone to do it for you.
Paul
_______
98 E300

Depends on the type of fault code as to how long it will take to clear. The light might go out sooner. A code won't reset for 40 warm-up cycles without being reset. Disconnecting the battery will reset the whole car and the light. Depending on the car that could be a real bad thing to do.

Upon reseting with a code reader or scan tool most emissions stations will then require the monitors to run. This will require proper application of a drive cycle. In reality depending on model the monitors can take some time to run.