OBD codes / P0171 / Toyota RAV4
P0171 on a Toyota RAV4
System Too Lean (Bank 1)
2.4L 2AZ-FE, 2.5L 2AR-FE fours and 3.5L 2GR-FE V6 (bank 1).
What P0171 usually means on a RAV4
P0171 tells you the RAV4 is running lean on bank 1 — the ECU is adding fuel to compensate for extra air or a fuel shortfall. On these engines the usual causes are a dirty mass-airflow sensor or a vacuum leak from an aging PCV hose or intake gasket. Higher-mileage RAV4s can also drift lean from a weak fuel pump or tired injectors. It may idle roughly, hesitate, or surge, and a bad enough lean condition can misfire.
Most likely causes on this model
- Dirty MAF sensor
The RAV4's hot-wire MAF gets contaminated and under-reports airflow; cleaning frequently clears it.
- Vacuum leak
Cracked PCV hoses or a hardened intake gasket let in unmetered air on older RAV4s.
- Weak fuel delivery
A tired pump or dirty injectors push trims lean under load; on newer A25A models check the pump recall.
- Failing air-fuel sensor
The Denso upstream sensor slows with age and misreports the mixture.
What it costs on a RAV4
Cleaning the MAF or replacing a vacuum hose is cheap and fixes most RAV4 P0171 cases; parts are easy to access on the four. A fuel pump or AF sensor is a larger spend. Read live fuel trims first, and on newer RAV4s check whether the low-pressure pump recall covers the work.
Year, engine and mileage change the answer. Get a diagnosis for your RAV4 — it weighs these causes against your exact configuration and real complaint data.
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Toyota RAV4 problems & recalls by year
Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0171 behavior is covered on the main P0171 page. Confirm with a scan tool before buying parts.