2001 Toyota Corolla with engine code P0170, is it the oxygen sensor or mass flow sensor?

Question

2001 Toyota Corolla CE with engine code P0170, is it the oxygen sensor or mass flow sensor?

Answer 1

P0170 Fuel trim lean Bank 1

 The more likely cause for a lean condition is with vacuum hose being disconnected which should be check first. If those area is secure, then the more likely cause would be the mass air flow sensor. What happen is the mass air flow tends to get coated from fine debris that does get pass the air filter element, you can cure a lean code condition with a MAF cleaner that is readily available at a auto part shop

Answer 2

P0170 Toyota Code - Fuel Trim Malfunction Bank 1
Read more: https://www.autocodes.com/p0170_toyota.html