DTC P1131 - Lack of Upstream Heated Oxygen Sensor Switch

[mark0101]

DTC P1131 - Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

So which O2 sensors do I need to replace?

 

[wood_e]

I would look for vacuum leaks before I change the O2 sensor.

 

[mark0101]

Well I am getting bad gas mileage, so I am pretty sure it needs an O2 senors. So does it need the ones in the front or the back? It has 110K.

 

[Abbens]

does the code say if its pre or post cat?

 

[mark0101]

does the code say if its pre or post cat?

what I posted is what it says on the websites for the code DTC p1131. I am guessing its the one before the cats, but I want to know which one before I replace them.