What are the common causes of P2191?

A dirty or faulty mass airflow sensor. A weak oxygen sensor. An intake manifold or vacuum leak. Clogged or dirty fuel injectors on bank 1. A weak fuel pressure regulator.

Read the fuel trims on bank 1 on a scan tool under load. Check for intake and vacuum leaks. Clean the mass airflow sensor. Check the fuel pressure and the injectors. Replace the bank 1 oxygen sensor if its signal is lazy. Clear the code and retest.

P2191

System Too Lean at Higher Load Bank 1

System: Fuel and air metering (P code)
Lamp: Check Engine Light
Category: Powertrain - Fuel/Air Metering

What it means

P2191 means System Too Lean at Higher Load Bank 1.

Check these first

A dirty or faulty mass airflow sensor
A weak oxygen sensor
An intake manifold or vacuum leak
Clogged or dirty fuel injectors on bank 1
A weak fuel pressure regulator

What to do next

Read the fuel trims on bank 1 on a scan tool under load
Check for intake and vacuum leaks
Clean the mass airflow sensor
Check the fuel pressure and the injectors
Replace the bank 1 oxygen sensor if its signal is lazy
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.