Running Too Lean While Enjoying Spirited Driving In Your Vehicle Is One Of The Leading Causes Of Expensive Engine Damage. Autometers Narrowband Air/Fuel Gauges Pair With Older Oxygen Sensors To Warn Of Lean Burn Conditions Under Heavy Engine Load. Connects Directly To The Factory O2 Sensor On Many Applications Or Uses The Autometer 2244 Narrowband O2 Sensor. Not Compatible With 5 Wire Air/Fuel Sensors.