2001 Toyota Corolla - intermittent CEL

Check Engine Light keeps coming off and on; especially after long idles at stop lights. The Mass Airflow sensor was replaced (11/19/19); Oxygen Sensor replaced (11/11/19); Intake Manifold Gasket and Throttle Body Mount Gasket replaced (9/28/2020). It was fine, but has now come back on and off a couple times since then.

Have the codes read and post back and please post the mileage.

1 Like


The code on the 2001 Toyota Corolla was P0171. It has about 144,00 miles.

The mass airflow sensor is dirty. Remove it and clean it with carburator cleaner. A dirty air filter is the cause for this part to go bad.Make sure you buy a new air filter and replace it.

Check for any air leaks in the air intake duct.


If air leaks into the engine after the MAF sensor, it’ll set that code.


Thank you. I will give these things a try!