Estimates Exhaust and Emissions Front Oxygen Sensor Replacement

Toyota 4Runner Front Oxygen Sensor Replacement

An oxygen sensor replacement is usually a pretty straightforward and affordable task. We stress the term usually because replacement cost can vary, depending on what type of car you have.

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Range for All Cars

$90.58 $1010.5

This range covers an average Front Oxygen Sensor replacement per set. Tell us your car to get a guaranteed price from RepairSmith.

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Toyota 4Runner Front Oxygen Sensor Replacement

RepairSmith offers upfront and competitive pricing. The average cost for Toyota 4Runner Front Oxygen Sensor Replacement is $383. Drop it off at our shop and pick it up a few hours later, or save time and have our Delivery mechanics come to you.

Quoted on
2002 Toyota 4Runner
SR5 • 136,481 miles
Berkeley CA 94704
Oct 26, 2020
$1,349 - $1,649
1996 Toyota 4Runner
3.4L V6 • 260,000 miles
Las Vegas NV 89123
Jul 15, 2020
$225 - $275
2008 Toyota 4Runner
4.0L V6 SR5 • 160,000 miles
La Crescenta CA 91214
Jun 29, 2020
$209 - $255
2005 Toyota 4Runner
• 188,000 miles
National City CA 91950
Jun 24, 2020
$251 - $307
2008 Toyota 4Runner
4.0L V6 • 103,000 miles
Lakeside CA 92040
May 4, 2020
$209 - $255
2003 Toyota 4Runner
4.0L V6 • 211,811 miles
Los Angeles CA 90011
Mar 25, 2020
$232 - $284
2000 Toyota 4Runner
3.4L V6 • 150,000 miles
Hayward CA 94544
Mar 13, 2020
$225 - $275
1995 Toyota 4Runner
3.0L V6 • 275,000 miles
Hemet CA 92544
Mar 11, 2020
$238 - $290
2001 Toyota 4Runner
3.4L V6 • 180,000 miles
Newport Beach CA 92663
Mar 2, 2020
$306 - $374
2007 Toyota 4Runner
4.0L V6 Sport • 190,000 miles
Mission Viejo CA 92691
Feb 17, 2020
$196 - $240
Last Updated:
Nov 13, 2020 5:47 PM
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What is a Front Oxygen Sensor?

This might blow your mind but…oxygen sensors (O2s) are sensors that measure oxygen. Yep, the sensors calculate the amount of oxygen in the exhaust stream, then share that information with your car’s main computer. Most modern cars have at least two oxygen sensors: one before the catalytic converter and one after the catalytic converter. In case you were wondering, the catalytic converter, which is located in the exhaust system, is an emissions control device that cleans up the fumes leaving your engine. Anyhow, the front oxygen sensor (also known as an upstream oxygen sensor) is a key input to your car’s computer for fuel control. The computer uses information from the sensor to estimate the engine’s air-fuel mixture. Then, it adjusts fuel delivery accordingly. On the other hand, the rear oxygen sensor (also known as a downstream oxygen sensor) primarily monitors the performance of the catalytic converter. The rear sensor has very little, if any, input regarding fuel control. Oh, and one more thing – most modern oxygen sensors have built-in heaters. When you first start your engine when it’s cold, the heater element gets the sensor nice and toasty. That allows the sensor to get up-to-speed and begin operating more quickly.

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Symptoms of a Failing Front Oxygen Sensor

Check engine light

If your car’s oxygen sensor isn’t doing its job, chances are, the computer will notice and turn on the check engine light. The device will also store corresponding diagnostic trouble codes (DTCs) in its brain. Your mechanic can retrieve said codes using an electronic device, called a scan tool.

Poor engine performance

The front oxygen sensor is a primary input to your car’s computer for fuel control. And guess what that means? If the sensor is out to lunch, the computer may end up giving your engine too much or too little fuel. As a result, you may experience performance problems, such as rough running, lack of acceleration and stalling.

Reduced fuel economy

As was mentioned, the front oxygen sensor is a key input to your car’s computer for fuel control. As such, it can confuse the computer and cause it to throw the engine’s air-fuel ratio out of whack, killing your gas mileage.

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How urgent is Front Oxygen Sensor Replacement?

Typically, a bad front oxygen sensor won’t leave you stranded. But it can cause your car to run poorly. Although somewhat rare, a faulty oxygen sensor can also damage other components, such as the catalytic converter. And trust us, catalytic converters are expensive. So, you don’t want to be buying a new one.

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