Why is it everyone starts with air filter for P0172 code?

Question

The air filter has been replaced, it seems every car I've scoped says bank 1 too lean. This is getting old!

Answer 1

Hi there

This code is for bank 1 to rich, not to lean. Typically a dirty air filter can cause this issue. There are several other causes that can contribute to it as well. Faulty O2 sensor, leaking fuel injector, just for an example. Here is some more info on the code for you.

P0172 TOYOTA - System Too Rich Bank 1

Read more: https://www.autocodes.com/p0172_toyota.html