Toyota 4Runner · Diagnostic Trouble Code
P0171 — System Too Lean (Bank 1)
Quick overview of P0171 on your Toyota 4Runner. Read the full diagnosis guide, then find the repair guides for your vehicle below.
Repair guides that fix P0171
Toyota 4Runner
2010-2024 Toyota 4Runner — MAF Sensor Replacement
Cleaning and replacing the MAF sensor.
Toyota 4Runner
2010-2024 Toyota 4Runner — PCV Valve Replacement
A stuck PCV valve is a classic lean-code cause.
Toyota 4Runner
2010-2024 Toyota 4Runner - Engine Air Filter Replacement
A restricted air filter can skew the air-fuel mixture.
Toyota 4Runner
2010-2024 Toyota 4Runner — Check Engine Light / OBD2 Diagnosis
What that light means and what to check first.
General diagnostic information, not a factory service procedure. If you're unsure, have a qualified technician confirm the diagnosis before buying parts.