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Mercedes-Benz R350 Rear 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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Average Shop Price $428
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This range covers an average Rear Oxygen Sensor replacement. Tell us your car to get a guaranteed price from RepairSmith.

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Mercedes-Benz R350 Rear Oxygen Sensor Replacement

RepairSmith offers upfront and competitive pricing. The average cost for Mercedes-Benz R350 Rear Oxygen Sensor Replacement is $416. 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.

Car
Location
Quoted on
Price
2012 Mercedes-Benz R350
3.5L V6 4Matic • 138,000 miles
Tujunga CA 91042
Nov 18, 2020
$383 - $469
2011 Mercedes-Benz R350
3.5L V6 4Matic • 24,000 miles
Moraga CA 94575
Nov 18, 2020
$346 - $422
2007 Mercedes-Benz R350
3.5L V6 4Matic • 40,000 miles
Inglewood CA 90301
Nov 14, 2020
$390 - $476
2011 Mercedes-Benz R350
3.0L V6 Turbo Diesel Bluetec 4Matic • 100,000 miles
Los Angeles CA 90039
Nov 12, 2020
$376 - $460
2009 Mercedes-Benz R350
3.5L V6 4Matic • 120,000 miles
Dublin CA 94568
Nov 9, 2020
$354 - $432
2011 Mercedes-Benz R350
3.5L V6 4Matic • 102,000 miles
Ontario CA 91762
Nov 9, 2020
$380 - $464
2010 Mercedes-Benz R350
3.5L V6 4Matic • 100,000 miles
Fairfield CA 94534
Oct 27, 2020
$357 - $437
2012 Mercedes-Benz R350
3.5L V6 4Matic • 65,000 miles
Temecula CA 92591
Oct 23, 2020
$404 - $494
2011 Mercedes-Benz R350
3.0L V6 Turbo Diesel Bluetec 4Matic • 135,000 miles
Alamo CA 94507
Oct 1, 2020
$392 - $479
2009 Mercedes-Benz R350
3.5L V6 Base • 23,000 miles
Somis CA 93066
Sep 20, 2020
$355 - $433
Last Updated:
Dec 17, 2020 6:25 PM
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What is a Rear 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 Rear Oxygen Sensor

Check engine light

If your car’s rear 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.

Failed emissions test

Is it time for your routine emissions test? Well, guess what – you’re not going to pass if the check engine light is on from a bad rear oxygen sensor. You also won’t pass if the rear oxygen sensor is out to lunch and it’s preventing your car’s computer from running its system self-tests.

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How urgent is a Rear Oxygen Sensor Replacement?

The rear oxygen sensor is less of a troublemaker than the front oxygen sensor. For the most part, the rear oxygen sensor just polices the catalytic converter. So, it’s unlikely to leave you stranded and it shouldn’t cause any additional harm to your vehicle.

But it will keep that annoying check engine light illuminated and, really, do you want to look at that thing every day? Plus, a bad rear oxygen sensor can cause you to fail a state emissions test – and nobody wants that.

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