02 Sensors, Bank 2 downstream

To access Bank 1 Sensor 1 you need to know what it means. Some of what I write you may already know. Every engine that has one cylinder head has one bank. Every engine that has two cylinder heads has two banks. Bank 1 always contains cyl. 1. On this engine, Bank 1 contains cylinders 1-3-5 and Bank 2 contains cylinders 2-4-6. Now lets talk about sensor 1. Each cylinder head has its own catalytic converter and each catalytic convertor has two 02 sensors. The Upsteam 02 sensor is Sensor 1 (the sensor before the CAT). The Downstream 02 sensor is Sensor 2 (sensor after the CAT). You are looking for the Upsteam 02 sensor on bank 1. I'm also proving a video that is similar to what you are working on and will need to do, to access that 02 sensor. Any questions, please write back. Good Luck.
https://www.youtube.com/watch?v=GAMbYw6NfMU

You need to get a code reader cheap ones are 50 .00 dollars or so or a parts store will clear it for free but remember they want to sell you parts .
Its a 6 or an 8 bank 2 sensor is usually on the exhaust manifold opposite side of #1 cylinder .
However oxygen sensors need to reach 600 degrees F before they start to work at all so the problem could be with the heating element witch needs to draw out side air into the sensor to compare with exhaust gas oxygen levels The air will come in through the wires in the back of the 02 unit if no outside air can get in the sensor it won't work correctly .So try cleaning the wires that feed the sensor first might save you some money

Hi Jesus, Im AL the owner of Big As Auto Repair.

If you have a 4 cylinder engine then you will only have two 02 sensors 1/1 is upstream and 1/2 is downstream. Upstream is the one closet to the engine and downstream is the one farther away from the engine.

If you have a six OR eight cylinder engine you will have four 02 Sensors. 1/1 means Bank One Sensor One. 1/1 and Bank one means right bank and right bank means the side with the number 1 spark plug. SO, 1/1 means, "Right Bank" Upstream 02 sensor. 1/2 means, "Right Bank" Downstream 02 sensor.

2/1 means, "Left Bank" Upstream 02 sensor and 2/2 means, "Left Bank" Downstream 02 sensor. Hope this helps and please visit my auto-repair-website at: http://www.bigasautorepair.com/

You did not say what your car was ,however most newer cars use 2 oxygen sensors per bank, if it is a 4 cyl replace downstream o2 sensor,if 6 or 8 cyl bank 1 sensor 2 is downstream sensor on bank that has cyl 1 on it.upstream sensor is in front of catalytic converter downstream is after the cat

Try resetting the codes by removing both terminals on the battery for 10 minutes. After the codes should be rest if they do not come back on the sensors are fine.

Here is the low-down on oxygen sensors, and their location designations explained:

Oxygen sensors are screwed into the exhaust system at various points. Some people say that there are 4 oxygen sensors, but technically, that is not correct. Only the front 2 are considered oxygen sensors.

These oxygen sensors are screwed into the exhaust pipe or directly into the exhaust manifold, one on each bank. Because they are in front of the catalytic converter, this is often referred to as 'upstream'.

The other 2 are actually called catalyst monitors. They are oxygen sensors, but they serve a different purpose. They monitor the activities of the catalytic converters, thus the name, catalyst monitors. They are screwed into the exhaust one on each bank, after, or downstream, of the catalytic converters.

On a 4 cyl engine, there are only a total of two such sensors, the one in front of the catalytic converter is the O2 sensor, the one behind the cat is the catalyst monitor.

The location names for them are as follows:

• On a 4 cyl, the front / upstream is called "bank 1 sensor 1" and the rear / downstream sensor is called "bank 1, sensor 2."
  
  
• On a V6 or V8 engine:
  
  
  • the passenger side bank on a forward facing engine, or the bank closest to the firewall on a transverse mounted engine, is bank number 1, so the forward / upstream sensor on that bank would be "bank 1, sensor 1."
    
    
  • The driver's side bank (forward facing mount engine), or front bank (transverse engine) would be bank number 2, thus the forward / upstream sensor on that bank would be "bank 2, sensor 1," and the rearmost / downstream sensor on that bank would be "bank 2, sensor 2."

This involves the front oxygen sensor on bank 1 sensor 1. This code indicates the engine air fuel ratio is not being adjusted by the oxygen sensor signal or the ECM as expected to do so, or not adjusted as often as expected to do so once the engine is warmed or under normal engine use. --------- There are two 02 sensors.That are before and after catalytic converter. Bank 1 sensor 1 (upstream/precatalytic converter) and bank 1 sensor 2 (downstream/post catalytic converter).
------------ But if possible replace both.The bank 1 as well as bank 2. Replacing both at a time is always advisable.--------- This should help.Thanks.Helpmech.

Well upstream from the Catalatic Converter means towards the engine and that would be the location for Sensor #1 on both sides of the engine. And Downstream would be away from the engine past the Catalatic Converter For Sensor #2 on both sides of the engine. Bank 1 or Bank 2 would indicate which side of the engine the trouble is on. ( Bank #1 is the side of the engine that contains #1 Cylinder. Please remember if you are going to change one 02 Sensor then you should change all of them and be sure to clear all codes after all repairs are finished. that will turn the check engine light off. Good Luck and have a good XMASS.

bank 1 is the drivers side bank, so b1s1 would be the drivers side closest to the engine. if the truck is equipped with several 02 sensors then bank 2 or b2s1 would be passenger side closest to the engine. those are called upstream o2 sensors and the others downstream b1s2 and b1s2 b= bank 1= drivers side s=sensor 2=downstream. hope this helps.

BANK ONE IS THE REAR BANK OF CYLINDERS AND TWO THE FRONT BANK