Oxygen Sensor question
Hi everyone. I am new to this site and was hoping someone could help me?
I am trying to fix my moms 1997 F150 for her. It is 6 cyl., 4.2L. It has 55,000 miles.
Her check engine light came on recently and I went to Autozone and rented one of the OBD II scanners.
I got the following codes:
P0135--O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0136--O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0141--O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0155--O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P0161--O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
I am now wondering what this all means.? I think I know that Bank 1 is by cylinder #1 and Bank 2 is by the drivers side. I also know that Sensor 1 is between the exhaust manifold and the cat. and that Sensor 2 is between the cat. and the muffler. Right? With the codes I got....do I just replace all 4 sensors? Since she's got 55,000 miles, is it time to replace them anyways?
Any responses back regarding this subject will really help.
THANK YOU in advance.