Were do i find an 02 sensor p0154 and p0155 on an 2002 avalanche with a 5.3L engine

Your exhaust has four 02 sensors. Code PO154 refers to no activity at bank two, sensor one.,Typically 02 sensors are good for up to 100K miles, after that their performance declines. You can try removing the sensor and shake it closely, next to your ear ( listen for a rattle). If you hear a noise while you are shaking it. The 02 sensor is junk. The side that Cylinder #1 is on is "Bank one" the other side is "Bank Two". Sensor one refers to the upstream senor (the sensor located before the CAT. Sensor Two would refer to the "Down Stream" sensor. Which refers to the 02 sensor located after the CAT. I hope that helps. Please write back if you have more details or questions. Good luck.

code p0154 refers to heated oxygen sensor (HO2S) 1 bank 2 -- no activity detected===causes --wiring---HO2S---= ECM
it also refers to oxygen sensor (O2S) --no activity detected--===causes --- wiring---O2S sensor---ECM. May be you did not replace the sensors causing the fault.

Error Code: P0154
Description:
Heated Oxygen Sensor (HO2S) 1 , Bank 2 - No Activity Detected
Problem areas:
- Wiring.
- Open circuit in signal wire, between Heated Oxygen sensor 1, Bank 2 and ECM. (Must check and confirm)
- Heated oxygen sensor (HO2S).
- Engine control module (ECM).

P0171 System too Lean (Bank 1)
P0174 System too Lean (Bank 2)
P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
P0134 02 Sensor Circuit No Activity Detected (Bank I Sensor 1)

http://www.obd-codes.com/p0134

P0154 02 Sensor No Activity Circuit

P0154 definition 02 (Oxygen sensor) circuit no activity detected bank 2 sensor 1, You need to test the heater circuit for its 12 volts and test the ground, its basically a dead 02 sensor,If you have a misfire you would have code as lean activivty, basically there is no lean to rich activity for this code to come on

both codes point to the oxygen sensor on bank 2 sensor 1 ..
that would explain the rough running also .. the engine will default to a rich condition ...

p0154 indicates no activity on bank 2 sensor 1 oxygen sensor
p01153 is showing "low switching" for bank 2 sensor 1 oxygen sensor ...

there may be a wiring pigtail coming from the sensor. that plugs into another connector a few inches away .. check that connector for damage or corrosion .. if its ok then you likely need a new oxygen sensor ..

its not a good idea to continue driving with this condition since it will eventually damage the catilytic converter. that is probably getting very hot now with the extra load of fuel ..

P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)

Check for the following:
1. A poor connection or damaged wiring harness. Inspect the harness connectors for :

Backed out terminals
Improperly formed or damaged terminals
Poor terminal to wire connection
Damaged harness

2. A malfunctioning HO2S heater on heater circuit

P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
THIS IS THE SENSOR BEFORE THE CAT CONVERTER
P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)
SAME SENSOR, WHEN THEY SAY BANK 2 IT IS THE BANK OF CYLINDERS OPPOSITE THE BANK THAT HAS #1 CYLINDER IN IT,
MAKE SURE THE SENSOR IS CONNECTED AND THAT THE CONNECTOR IS NOT DAMAGED.

P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1). You have a bad O2 Sensor. I dont know how your O2 sensors are labeled, but your local auto parts store should help you with that one. Good luck to you. Let me know if you have anymore questions.

Sincerely,

JC