Mercedes-Benz E420 Oxygen Sensor Replacement at your home or office.

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Oxygen Sensor Replacement Service

How much does a Oxygen Sensor Replacement cost?

On average, the cost for a Mercedes-Benz E420 Oxygen Sensor Replacement is $372 with $277 for parts and $95 for labor. Prices may vary depending on your location.

CarServiceEstimateShop/Dealer Price
1995 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Front/Upper/Upstream ReplacementEstimate$759.71Shop/Dealer Price$938.39 - $1435.06
1994 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Front/Upper/Upstream ReplacementEstimate$739.71Shop/Dealer Price$918.42 - $1415.11
1997 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Rear/Lower/Downstream ReplacementEstimate$686.15Shop/Dealer Price$851.47 - $1307.99
1994 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Rear/Lower/Downstream ReplacementEstimate$648.11Shop/Dealer Price$803.88 - $1231.84
1995 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Rear/Lower/Downstream ReplacementEstimate$648.11Shop/Dealer Price$803.95 - $1231.96
1997 Mercedes-Benz E420V8-4.2LService typeOxygen Sensor - Front/Upper/Upstream ReplacementEstimate$1309.79Shop/Dealer Price$1631.02 - $2555.27
Show example Mercedes-Benz E420 Oxygen Sensor Replacement prices

What is the Oxygen Sensor all about?

With each new model year, manufacturers are adding more oxygen sensors to better manage engine operation. Some high performance engines have an oxygen sensor for each cylinder as well as one for the rear of each catalytic convertor. The sensors are located either underneath the hood or underneath the car. The oxygen sensors are connected (screwed) to the exhaust pipe, either in front or back of the catalytic converter. The front (upstream) sensors measure the amount of oxygen in the exhaust system. The purpose of the front oxygen sensor(s) is to measure how rich or lean the gases are as the gases exit the combustion chamber. Depending upon whether the exhaust gas is lean (high in oxygen content) or rich (low in oxygen content), the amount of fuel entering the engine is adjusted by the engine management computer to try and maintain an ideal mixture that produces the lowest emissions output from the catalytic convertor.

Rear (downstream) sensors are located behind the catalytic converter. The purpose of the rear oxygen sensor(s) is to monitor the oxygen content of the exhaust gases leaving the catalytic convertor.

If one or more of the oxygen sensors are faulty, your car may not pass the emissions test. If you drive your car with a faulty oxygen sensor, you may get poor gas mileage and it can damage the catalytic converter.

Oxygen Sensor-MATROX-1

When replacing the oxygen sensor remember:

  • Many oxygen sensors are damaged by leaking oil or coolant. If that is the case, the cause of that leak needs to be identified and repaired, or else the replacement oxygen sensor will be damaged as well.
  • New vehicles require specific oxygen sensors, and not the universal sensors that were common prior to 1996.

How it's done:

  • Scan the computer in the car for codes.
  • Inspect for vacuum leaks and holes in the exhaust system.
  • Remove and replace the oxygen sensor if it is bad.
  • Check electrical connections.
  • Check for proper operation of oxygen sensors.
  • Clear diagnostic codes.
  • Test drive car.

Our recommendation:

Keep up with the tune-ups. If check engine light is on, don't drive the car too long without getting it inspected. If check engine light is flashing, pull over and get the car towed to avoid costly repairs. Ask the mechanic to inspect the vacuum hoses and leaks in the exhaust system. If the vacuum hose or exhaust system is leaking, it will display an oxygen sensor fault code. Replacing an oxygen sensor may not fix the problem.

What common symptoms indicate you may need to replace the Oxygen Sensor?

  • Check Engine light is on.
  • Car is getting poor gas mileage.
  • Emission test fails.

How important is replacing the oxygen sensor?

Your vehicle has multiple oxygen sensors, and they all help the car run optimally. The front sensors measure how much oxygen is in the exhaust stream to measure how rich or lean the gases leaving the gas chamber are. The rear sensors measure the oxygen content of the gases as they leave the catalytic converter. The oxygen sensors then relay this information to your vehicle’s electronic control unit, so that it can adjust as necessary. Because cars depend on an ideal fuel-to-air ratio to function optimally, the oxygen sensors are leaned on for engine performance. When your oxygen sensors fail your car will run less smoothly, get worse mileage, and have worse emissions.

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Excellent Rating

(21)

Rating Summary
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16
2
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Bill

21 years of experience
23 reviews
Bill
21 years of experience
Mercedes-Benz E420 V8-4.2L - Oil Change - Aliso Viejo, California
Knowledgeable, honest, and professional!

Tien

23 years of experience
903 reviews
Tien
23 years of experience
Mercedes-Benz E420 V8-4.2L - Transmission Fluid Service - Berkeley, California
Prompt and competent.

Jesus

16 years of experience
68 reviews
Jesus
16 years of experience
Mercedes-Benz E420 V8-4.2L - Pre-purchase Car Inspection - Long Beach, California
I requested a pre purchase inspection for a car about 200 miles away from where I live. Jesus was on time, responsive, and very pleasant to work with. He kept me abreast of his inspection and provided me his professional feedback on the status of the vehicle. He followed up with a comprehensive and easy to understand report of his findings. Awsome service and awesome professional mechanic. Thank you.

Brian

22 years of experience
132 reviews
Brian
22 years of experience
Mercedes-Benz E420 V8-4.2L - Oil Change - Springfield, Virginia
It's the second time Brian has worked on my car (I should've left a comment the first time, but forgot). Each time he not only has been efficient, he's been a real professional. We also have a good time while he works. He's worked on my car at home and at my office and no matter where he works, I've been very satisfied. Owning an older model Mercedes Benz, I always worry that others won't treat it the way I feel it should be treated, but Brian does. He's knowledgeable and gentle with every part he handles and every screw or bolt he turns--I appreciate that. If my first two experiences are any indication of the future, my car is in good hands. Thanks Brian.

Excellent Rating

(21)

Rating Summary
16
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2
16
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Number of Mercedes-Benz E420 services completed
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