Why it matters: O2 sensors feed critical data to your ECU, helping maintain the ideal air-fuel ratio for performance, efficiency, and emissions control. Reading the signals: Healthy upstream sensors ...

What are lean codes: P0171 and P0174 indicate a lean fuel mixture on Bank 1 and Bank 2, often detected by upstream oxygen sensors. Why they matter: Lean conditions can cause misfires, hesitation, ...

We earn commissions from purchases you make using links in our articles. Learn more. If your car experiences poor fuel economy, lacks power, feels sluggish, idles rough, or has an illuminated check ...