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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11295
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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How do you replace the front O2 sensor 2000 chevy impala 3.8l

Resolved Question:

How do you replace the front O2 sensor 2000 chevy impala 3.8l? Access behind engine seems very tight. Thx.
Submitted: 4 years ago.
Category: Chevy
Expert:  Randall C replied 4 years ago.
Hello, it is tight. You can however get to it once top cover off and maybe? move a couple smaller items located on the firewall that may be in you way. In the shop we many times have to use a swivel attached to the o2 socket then long extension. there just is really no other way but to try to get straight shot on it or use the swivel and a o2 socket with long extension.

NOTE: The Heated Oxygen Sensor (HO2S) and the Oxygen Sensor use a permanently attached pigtail and connector. Do not remove this pigtail from the Heated Oxygen Sensor. Damage or the removal of the pigtail or the connector could affect the proper operation of the sensor.

Take care when handling the HO2S and the O2S. Keep the in-line electrical connector and the louvered end free of grease, dirt, or other contaminants. Also avoid using cleaning solvents of any type. Do not drop the HO2S or the O2S. Do not roughly handle the HO2S or the O2S.

Removal Procedure

IMPORTANT:


  • Take care when handling the heated oxygen sensor. The in-line electrical connector and the louvered end must be kept free of grease, dirt or other contaminants. Also, avoid using cleaning solvents of any type. Do not drop or roughly handle the heated oxygen sensor/catalyst monitor. A dropped sensor is a bad sensor.
  • The heated oxygen sensor may be difficult to remove when the engine temperature is below 48°C (120°F) . Excessive force may damage the threads in the exhaust manifold or the exhaust pipe.



  1. Turn OFF the ignition.
  2. If the HO2S 2 is being replaced, raise the vehicle.



  1. If HO2S 1 is being replaced, remove the fuel injector sight shield.
  2. Disconnect the HO2S sensor electrical connector.
  3. Carefully back out the heated oxygen sensor. Installation Procedure IMPORTANT: A special anti-seize compound is used on the heated oxygen sensor threads. The compound consists of graphite suspended in fluid and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or service sensors will already have the compound applied to the threads. If a sensor is removed from the engine for any reason and is reinstalled, the threads must have anti-seize compound applied before reinstallation.



  1. Coat the threads of the heated oxygen sensor/catalyst monitor with anti-seize compound P/N(NNN) NNN-NNNN or equivalent, if necessary.



  1. Install the heated oxygen sensor. Tighten Tighten the heated oxygen sensor to 41 N.m (30 lb ft).
  2. Connect the HO2S sensor electrical connector.
  3. If HO2S 2 is replaced, lower vehicle.
  4. If HO2S 1 is being replaced, replace the fuel injector sight shield.
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11295
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
Randall C and other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
Thank you - will pay after two more questions: 1.)Can I buy O2 sensor socket from a local Autozone or Pep Boys or the like? 2.) What size socket is it?
Expert:  Randall C replied 4 years ago.
O2 sensors are 7/8 or 22 mm and yes 100% you can buy the socket at pepboys, AZ or advance with no problem ( unless sold out:) It will be a deep socket with a slot cut down one side for the wires to slide into. BTW: You do NOT want to try removing an o2 sensor unless the engine is 100% cold. You can strip it
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11295
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
Randall C and other Chevy Specialists are ready to help you

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