P0171 on a Hyundai: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

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

What P0171 means on a Hyundai

On a Hyundai, P0171 means bank 1 is running lean — too much air or not enough fuel — and the engine computer has hit its limit adding fuel. The computer uses the MAF sensor and oxygen sensors, and a lean mixture that persists sets P0171.

Is P0171 common on Hyundais?

P0171 appears on Elantras, Sonatas, and Santa Fes with higher mileage. A dirty MAF sensor and vacuum leaks are the most common causes, and a worn PCV valve can also let in unmetered air.

Commonly reported on: Elantra, Sonata, Santa Fe, Tucson.

Symptoms

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

Common causes

most common: Vacuum leak (hoses, intake 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 repair vacuum leaks	Yes	$10–100
Clean the MAF sensor with MAF cleaner	Yes	$10–20
Replace the PCV valve	Yes	$10–50
Replace a weak fuel pump or clogged fuel filter	Mechanic	$300–700