Can someone tell me which o2 sensor is bank 1 sensor 1.

im getting code P0135 o2 sensor heater circuit and want to change the sensor out so I can pass an emissions test.

 

Bank one is the driver's side (LH from where you sit driving) bank two is the RH side.

Sensor one is before converter, and sensor two is after converter.

 

Sensors before the converter closer to the engine are down stream or upstream?

 

If I'm getting an error on one of the O2 sensors and I just bought the truck, is it a good general practice to just replace all 4, or just the one that's coding? Obviously would like to not spend what I don't have to.

 

Upstream (Position 1) is between the exhaust manifold and the catalytic converter. Downstream (Position 2) is after (downstream of) the catalytic converter.

I've owned my DII 17 years and the downstream O2s have not been replaced and have never thrown a code. If it ain't broke(n) don't fix it.

There are those who say the upstream O2 sensors should be replaced in pairs. Those people are often mechanics who are selling sensors and being paid to replace them. If it ain't broke(n) don't fix it.​​​​​​

 

Okay so sensor 1 is an upstream sensor correct?

 

Im only changing sensor 1 bank 1 which I知 assuming is the up stream sensor on the drivers side closer to the engine.

Correct?

sorry I知 a newbie.

 

Yes. Bank 1 sensor 1 is the upstream on the driver's side.

 

I have owned mine for 13 years and have never replaced the downstream sensors. I myself did replace both upstream at 120k miles just because I knew they were old and probably not switching as fast as they should. Finally am getting an intermittent code for one of the downstream sensors. Until it becomes a consistent problem, I am not going to do anything but clear the code as all the downstream sensors do is monitor the converter to make sure it is working.

 

I値l replace both upstream sensors, just found two Bosch for $110 on amazon.

Any tips on reaching and disconnecting the clip?