2004 Cadillac Seville bank 1 O2 sensor near fire wall is froze in place in the exhaust manifold and will not back out even with extreme pressure. Will heating area near threads and expand exhaust free the sensor??

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Hope this helps

Bank two are the even cylinders. Follow exhaust manifold on the side. You will find an O2 sensor just after or on the manifold, before the catalytic converter. Then, look after the catalytic and you should find another O2 sensor, this is the one you mention in your post.

bank 1 is the right hand bank looking at the rngine from the front on a convention car or the bank closest to the fire wall on an east west set up
o2 sensors are always after the cat converter
HO2S or heated oxygen sensor which are different to O2 sensors are always in the exhaust manifold or pipe before the cat converter

the back manifold ( closest to the fire wall) is bank l
there are not 2 x O2 sensors up stream
they are heated oxygen sensors (HO2S) and are in the manifold or exhaust pipe before the cat converter
The 2 x O2 sensors are after the cat converter in the exhaust pipe
so bank 1 sensor 1 is a HO2S sensor
there is a difference in the sensors as the HO2S report exhaust gas conditions to the ECM for fuel /air adjustments , have 4 wires and are heated to read the gas correctly
the after cat converter sensors ar O2 sensors and report on the cat converter action to further adjust the air /fuel mix in the ECM

So what do you want to know ? How to get in an replace O2 sensor ? That's what being a mechanic is all about ! Getting it done when other people can't .

It should be easy to find. It is between the exhaust manifold and the converter.

- Front Heated Oxygen Sensor Bank 1 harness is open or shorted
- Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Faulty Front Heated Oxygen Sensor Bank 1
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks

Replacing the O2 Sensor 1 usually takes care of the problem

The front heated oxygen sensor (or O2 sensor 1) is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The heated oxygen sensor 1 signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.

it is not an O2 sensor but a heated oxygen sensor that is in the exhaust manifold before the cat converter
heated oxygen sensor(HO2S) 1 bank 1 is the one against the fire wall
it is not a heater as such but has an internal heating system so that it reads the exhaust emissions correctly and adjusts the air /fuel settings in the ECM
normally has 4 wires
the oxygen sensor (O2S) is after the cat converters and is a completely different sensor to read a different exhaust gas

The DTC (Data Trouble Code) P0135 is for the O2 sensor Heater Circuit Bank 1 Sensor 1. Bank 1 will always be the cylinder bank with the number one cylinder and spark plug, and the number one O2 sensor will be located before the catalytic converter and usually at the rear of the exhaust manifold or just after it. According to the firing order diagram bank one is the cylinder bank that is closest to the fire-wall and there should be an O2 sensor located there around the rear of the exhaust manifold or just after it. If the engine is a 4 cylinder then it will be the O2 sensor before or up-stream of the catalytic converter. Check for any damaged wiring or loose wire connector at the O2 sensor and if they are alright then replace the O2 sensor and then re-set the check engine light. (The auto part store should re-set the check engine light for you if you purchase the O2 sensor from them, and be certain that it is the correct and assembled O2 sensor for your vehicle and not a put together universal O2 sensor)

Hi,
Bank 1 sensor 2 is on the firewall side of the engine, and is the bottom O2 sensor (the one furthest from the engine). It is accessed from below the vehicle.

it is on the back of the exhaust manifold on the back of the motor by the fire wall