O2 Oxygen Sensor for Buick Enclave Cadillac XLR SRX GMC Acadia 3.6LPrecision Stoichiometric Monitoring: GM LY7 & LLT 3. 6L 4. 6L Northstar O2 Sensor Who Its For: Engineered for owners of GMs Lambda and Sigma platform vehicles running the High Feature 3. 6L V6 (LY7 LLT) and the 4. 6L Northstar V8 (LH2) who are experiencing fuel trim errors or a loss in fuel economy. The Symptom: The factory oxygen sensors on the GM 3. 6L and 4. 6L engines are high wear items that eventually "lazy out," responding too slowly to changes