fault code p1296 came up on diagnostic. Car has been bogging down and losing gas mileage. Pretty sure its an o2 sensor(s) but wondering if anyone can tell me for sure.

 

try coolant temperature sensor faulty or thermostat

 

P1296 / Audi #17704 = Engine Cooling System Malfunction. This is usually due to a thermostat that is stuck open or opens too soon. The DTC (Diagnostic Trouble Code) sets when the ECM (Engine Control Module) does not see 80 degrees Celsius (176 f) or greater within the first 16 minuets of operation. Basically it means the car is not getting hot enough, soon enough.