How many o2 sensors is on a 2002 impala - 2002 Chevrolet Impala

because its not the sensor.
its the plug for the sensor .the wires.or it
is the cataletic converter/exhaust system
i just replaced my exhaust on my 07 chevy malibu same o2 sensor issue p0420 or something like that ?!
replace the converter and youll be fine i still have my old sensors in there that gave me the code :)
there not saying there bad but that the cat is bad.

You should have a primary and secondary O2 sensor, upstream and downstream. Pre-Catalytic converter and Post-Catalytic converter.
Which one did you replace?

you can apply pressure to the sensor while undoing it to force it out or you will have to cut out the thread area and get an O2 sensor bung hole replacement at an auto supply store and weld into place and install a new O2 sensor. bank 1 sensor 1 is located in the front pipe off the manifold that has cylinder #1 on and bank 2 sensor 1 is on the side that cylinder #2 is on like sensor 1. sensor 3 is the one just before the cat.

That is the downstream sensor.
This picture is the 3.4 engine

1. Reduced fuel economy
2. Increased exhaust emissions
3. Poor engine performance
4. Engine check light appears
5. Engine stalls during idling
6. A rotten egg odour emitting from the exhaust
7. Your engine surges or hesitates
8. Rich mixture

if you look on the back side of the engine closest to the firewall there will be one in the exhaust manifold. That one will be the bank 1 sensor 1 O2 sensor.

If you look under the car there will be one right after the catalytic converter. That will be the bank 1 sensor 2 O2 sensor

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Couple of notes - poor grade of fuel or additives can be coating O2 sensors. Next, when changing sensors are you disconnecting battery? If not a power surge can damage sensor and lastly check wiring harness and make sure wires are all clean and not scared along the way - could be shorting out.

I have a 2002 Impala with 3.8L, and just replaced my Bank1 O2.
It is located between the firwall and the middle of the engine, straight down past the spark plugs. Maybe 12 inches from the top of the engine.
As I recall the plug for the sensor is clipped to a bracket at about spark plug level.
I recommend using the crow foot style wrench to remove and install.

Hello! The #2 Oxygen Sensor is located "downstream" which means after the catalytic converter...The sensor is threaded and screws into the exhaust pipe to the rear of the converter...Downstream O2 Sensors are used to monitor catalyst efficiency while Upstream O2 Sensors have a pronounced effect on performance...Hence, engine runs fine...Problem is the vehicle will not pass inspection with a Check Engine Light on...The problem may be a bad ground, a contaminated sensor or a defective sensor...
Do you have a multimeter and a little experience using one? If not have the sensor replaced...If so, here is a procedure to check the vehicle's grounds...Set meter to X10 ohm scale...Place one probe on the center of the - battery post...The other on bare metal of the exhaust pipe...You'll need a long piece of 10Ga. wire...Reading must be zero or very close to it...If not, the O2 sensor is probably good and a ground strap needs to be installed...O2 Sensor pictured below...Cost is around $60 for the sensor and .5 hours labor...Guru.....saailer




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it is locared on the driver side on top of the transmision