What's the 2011 GMC Acadia oxygen sensor location?

The 2011 GMC Acadia is equipped with 4 oxygen sensors. Two are located on the front and underside of the motor and before and after the catalytic converter. Bank 1 Sensor 1 sits next to the firewall. The Acadia's O2 sensors are responsible for monitoring the amount of air or oxygen present in the fuel to determine whether the engine is running "rich" or "lean". When sensors start to fail oil and fuel consumption may increase, and You'll witness a rough idle, an illuminated "check engine" light, reduced power and acceleration and spark plugs mIS Firing. Over time a lack of timing and emissions control can damage the engine and exhaust parts. The cost to replace an O2 sensor on the Acadia averages $380-$400 in parts and labor.