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Normally Aspirated Engine Oxygen Sensor Replacement
 
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Pelican Technical Article:

Normally Aspirated Engine Oxygen Sensor Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$300

Talent:

****

Tools:

Oxygen sensor socket, 22mm wrench, flathead screwdriver, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

Oxygen sensors, anti-seize paste

Hot Tip:

Work with a cool exhaust

Performance Gain:

Remedy fault codes and maintain proper running engine

Complementary Modification:

Replace in pairs

Oxygen sensors monitor the exhaust stream, comparing the oxygen content in it to the oxygen content in the ambient air. When the oxygen content is low, sensor voltage is high. When oxygen content is high, sensor voltage is low. The voltage created by the sensor is sent to the DME (engine control module) to help maintain a proper fuel mixture. The mixture preparation is used to keep the catalytic converters running at peak efficiency. The oxygen sensors used in V70 models covered in this article have four wires. Two of which are for oxygen sensor heating and two for the signal. The heater is used to get the sensor online faster. Previously, exhaust heat was used. One wire supplied a ground to the sensor for the signal, and the other is for the sensor signal.

Oxygen sensors should be replaced every 100,000 miles. In a perfect world you could wait until 100,000 miles has gone by on your V70. Wait until a specified mileage and replace the sensor. However, these sensors fail prematurely, set oxygen sensor fault codes and reduce fuel economy. In this article, I will show you how to identify the location of all four oxygen sensors and how to replace them. You will need an oxygen sensor socket to remove the sensors and remember to always work with a cool exhaust. Oxygen sensors are fragile. Do not drop, as damage may occur. Also, keep the sensor tip clean when reinstalling.

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter. Sensor 1 or S1 refers to the sensor before the catalytic converter. Sensor 2 or S2 refers to the sensor after the catalytic converter.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

The pre-catalyst (Sensor 1) location for the O2 sensor is indicated by the green arrow.
Figure 1

The pre-catalyst (Sensor 1) location for the O2 sensor is indicated by the green arrow. The post-catalyst location is indicated by the (Sensor 2) red arrow.

To replace either of the sensors, start by locating the electrical connectors (green arrows).
Figure 2

To replace either of the sensors, start by locating the electrical connectors (green arrows). They are mounted to a bracket below the brake master cylinder.

Remove the hot air pipe from the exhaust manifold and move it toward the cylinder head (green arrow).
Figure 3

Remove the hot air pipe from the exhaust manifold and move it toward the cylinder head (green arrow).

The pre-catalyst connector (Sensor 1) is designated with the green arrow.
Figure 4

The pre-catalyst connector (Sensor 1) is designated with the green arrow. The post-catalyst connector (Sensor 2) is shown with the red arrow. Follow the harnesses down to the mounting clip (yellow arrow). Detach the mounting clip from the bracket by squeezing it and pulling it off.

Next, disconnect the electrical connector of the oxygen sensor you are replacing.
Figure 5

Next, disconnect the electrical connector of the oxygen sensor you are replacing. Disconnect the electrical connector by pressing the release tab (red arrows) and pulling the sensor side out (yellow arrows). Note the wiring harness color, factory sensors color code sensors to help when replacing. Locate the color of the sensor you loosened.

Replacing sensor before catalytic converter: Using an oxygen sensor socket (yellow arrow), remove the oxygen sensor from the exhaust manifold.
Figure 6

Replacing sensor before catalytic converter: Using an oxygen sensor socket (yellow arrow), remove the oxygen sensor from the exhaust manifold. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten. Then reroute the wiring harness and connect the electrical connector. When reinstalling the sensor, do not allow the harness to remain twisted. Be sure it is properly routed and tension free. Then reassemble and clear any engine fault codes using a Volvo scan tool.

Replacing sensors after catalytic converter: Oxygen sensors are located in the exhaust, behind the catalytic converters.
Figure 7

Replacing sensors after catalytic converter: Oxygen sensors are located in the exhaust, behind the catalytic converters. Follow the sensor harness up to the bracket (green arrow). Then cut the tie strap (inset).

Replacing sensors after catalytic converter: Using an oxygen sensor socket (red arrow), remove the oxygen sensor connection to the catalytic converter (inset).
Figure 8

Replacing sensors after catalytic converter: Using an oxygen sensor socket (red arrow), remove the oxygen sensor connection to the catalytic converter (inset).

Replacing sensors after catalytic converter: When reinstalling the sensor, do not allow the harness to remain twisted.
Figure 9

Replacing sensors after catalytic converter: When reinstalling the sensor, do not allow the harness to remain twisted. Be sure it is properly routed and tension free. Use a new tie strap to secure the harness to the bracket as it was before. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten it. Then reroute the wiring harness and connect the electrical connector. Then clear any engine fault codes using a Volvo scan tool.

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Comments and Suggestions:
abieker13 Comments: Thank you, I am learn good first time. my Car is 2001 Volvo V70 xc
July 19, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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