Easy step by step guide on how to replace an automotive engine exhaust oxygen sensor
P0135, P0141, P0147, P0155, P0161 and P0167, this information
pertains to most cars.
Difficulty Scale: 4 of 10
Before beginning, park the car on level ground and allow to cool, block the tires
to prevent the vehicle from moving. Lift the car with a floor jack in the manufacturers
recommend position, use jack stands to secure the car. Oxygen sensors are located
in the exhaust system so be careful of hot components. Make sure to wear protective
clothing, gloves and eye wear.
- Before the oxygen sensor should be removed
apply a light penetrating oil such as WD40 to help prevent thread and sensor damage.
Lubricating Oxygen Sensor
Step 2 - Some sensors are equipped with a heat
shield that must be removed before the sensor removal, this is performed by removing
any mounting bolts.
Step 3 - Because most of us do not have a sensor
removal tool, cut the sensor wires to ease the removal, a regular wrench will also
work if the wires need to be left intact.
Oxygen Sensor Heat Shield Removal
Oxygen Sensor Wires Cut
Step 4 - By using a regular socket it minimizes
potential damage to the sensor body and the threads, this technique helps avoid
stripping the old sensor upon removal.
Step 5 - Once the old sensor has been removed,
inspect the threads for damage which is common with these sensors.
Deep Well Socket Removal Tool
Step 6 - Then, locate and disconnect the wiring
connector, this step should be done before removing the sensor if the wiring is
Step 7 - Its important that the wiring harness
connectors are exactly the same, each sensor is unique to it's position and is located
in the system by its connector configuration. (Note: some replacement sensors have
a universal electrical connector that must be configured to the wiring of the old
Disconnecting Oxygen Sensor Wiring Connector
Step 8 - Compare the new sensor to the old sensor
to ensure a proper installation.
Oxygen Sensor Wiring Connectors
Step 9 - Most new oxygen sensor manufacturer's
include a small amount of anti-seize lubricant to help condition the mounting threads.
New Oxygen Sensor
Step 10 - After lubricating the threads and comparing
the wiring harness connector the sensor is ready for installation.
Lubricating Oxygen Sensor
Step 11 - Use a small wire brush to help clean
the threaded port to ensure a proper seal of the new sensor. Gently install the
new oxygen sensor by hand while keeping the wiring and connector free from bends.
New Oxygen Sensor
Step 12 - Most sensor installations can be performed
by using a normal 7/8 wrench, but when the sensor is obstructed by a heat shield
etc. it helps to have the installation-removal tool.
Installing New Oxygen Sensor
Step 13 - Gently tighten the sensor while keeping
wiring free from damage, these sensors need to be fairly snug to avoid leakage.
Oxygen Sensor Installation and Removal Tool
Step 14 - Once the sensor is tightened, reinstall
any heat shields or bracing that had to be removed.
Tighten Oxygen Sensor
Step 15 - After the heat shield has been reinstalled,
mount the connector to it's holder and reattach the connector back onto the wiring
harness. If the car has diagnostic trouble codes, they will need to be cleared.
Heat Shield Installation
or lambda sensor
Reconnect Sensor Wiring Connector
is used to determine the engine exhaust mixture which can then be controlled by the computer. These sensors are equipped with a heater
that can fail causing the check engine light to illuminate. The oxygen sensor is
designed to monitor the amount of oxygen that is in the exhaust system at any given second.
This is done by using an active chemical that when heated can act as a low voltage
generator. There are many conditions that can cause an oxygen sensor to miss-behave
even though there is nothing wrong with the sensor, to be sure the sensor is a problem
visit how to test an
. Older models will have just one sensor in the exhaust system
while newer cars will have as many as four sensors. The reason behind the multi-sensor
systems is control and monitoring capabilities. A multi-sensor system will be able
to monitor the exhaust gasses before and after the
Most sensors are designed with a heater element to aid the sensors functionality
when operating cold. Failure of this element is common and will warrant sensor replacement.
When a sensor or the heating element inside the sensor fails it will trigger a check
service engine soon light
in most cases. If this occurs connect a scanner tool
to access the diagnostic trouble codes
help pin point the failed sensor. Once the failed oxygen sensor has been located,
simply replace the sensor. When an O2 sensor fails it can cause the engine to
or rich depending on the failure
Tools and Supplies Needed
- Wrench set with large sizes
- Shop Towels
- Anti-Rust penetrating oil such as WD40
- Replacement Oxygen Sensor
- Wire Brush
- Use an anti rust treatment to help in the removal of the old sensor.
- A specially designed socket or wrench can be used to aid in the removal
of hard to access sensors.
Article first published 2016-11-28