Q: In my vehicle, the check engine light comes on and then goes off and it is now back on. I had a test done at local auto-parts store that showed a code of PO138. They told me this indicates a ...

We tested popular wideband O₂ controllers against lab-grade equipment to see how accurate their lambda readings really are under real engine conditions.

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 ...