P0171 on a Honda: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

A Honda with P0171 is drivable short-term, but a lean mixture can cause misfires and should be fixed soon.

What P0171 means on a Honda

On a Honda, P0171 means bank 1 is running lean — too much air or not enough fuel — and the computer has hit its limit trying to add fuel. Honda's ECM uses the MAF sensor and oxygen sensors to judge the mixture, and when it stays lean it sets P0171.

Is P0171 common on Hondas?

P0171 shows up on Accords, Civics, and CR-Vs with higher mileage. A dirty MAF sensor and intake hose vacuum leaks are the most common Honda causes, and a worn PCV valve can add unmetered air too.

Commonly reported on: Accord, Civic, CR-V, Odyssey.

Symptoms

Check engine light on
Rough idle
Hesitation when accelerating
Poor fuel economy

Common causes

most common: Vacuum leak from the intake hose or gaskets
common: Dirty or failing MAF sensor
common: Worn PCV valve
less common: Weak fuel pump or clogged fuel filter

How to fix it

Fix	DIY?	Typical cost
Inspect and fix vacuum leaks in the intake system	Yes	$10–100
Clean the MAF sensor with MAF cleaner	Yes	$10–20
Replace the PCV valve	Yes	$10–40
Replace a weak fuel pump or clogged fuel filter	Mechanic	$300–700