P0171 on a Lexus: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

Drivable for a short time, but a lean condition can cause rough idling and misfires, so get it checked soon.

What P0171 means on a Lexus

On a Lexus, P0171 means bank 1 is running lean, so the engine is getting too much air or not enough fuel. The Lexus engine computer has already added as much fuel as it can and still sees a lean mixture, so it turns on the check engine light.

Is P0171 common on Lexuss?

P0171 appears on Lexus models mostly at higher mileage, including the ES 350, RX 350, and IS with the 2GR-FE 3.5L V6 and older V6 engines. A dirty MAF sensor and cracked intake hoses are the usual causes. Lexus engines generally run clean, so a lean code usually points to an air leak or sensor issue, not the engine itself.

Commonly reported on: ES 350, RX 350, IS 250, GS 350.

Symptoms

Check engine light on
Rough or surging idle
Hesitation or lack of power
Poor fuel economy

Common causes

most common: Dirty or failing mass air flow (MAF) sensor
common: Cracked intake hose or vacuum leak
common: Clogged PCV valve or hose
less common: Failing upstream oxygen sensor
less common: Weak fuel pump or clogged fuel filter

How to fix it

Fix	DIY?	Typical cost
Clean the MAF sensor with MAF cleaner spray	Yes	$10–20
Inspect and replace cracked intake or vacuum hoses	Yes	$10–100
Replace the PCV valve	Yes	$15–60
Replace a weak fuel pump	Mechanic	$400–900