Difference between P0137,P1138 and P0037
 

P1138 O2 Sensor Heater Circuit Low Voltage (Bank 1 Sensor 2)

P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)

P0037 Bank 1 Sen 2 Heater Circuit Low


I used to have P0037 on my code reader and i havent even changed the rear 2 yet. (getting the Denso tomorrow) Now the code reader says P0137.

But then I see the reader also spits out P1138.

So what is the difference between those codes?