How many O2 sensors?

i want to know how many O2 sensors my car use

My car has 66000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
You have 2 oxygen sensors in your Chevrolet Equinox. One located before the catalyst and one after.

If you’re having any issues with these components, feel free to contact YourMechanic, as a certified technician can help you diagnose and replace these oxygen sensors if necessary.

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You have 2 oxygen sensors in your Chevrolet Equinox. One located before the catalyst and one after. If you`re having any issues with these components, feel free to contact YourMechanic, as a certified technician can help you diagnose and replace these oxygen sensors if necessary.
Your vehicle has two oxygen sensors. One is located before the catalytic converter and one is located just after the catalytic converter.
There will be one in front of the catalytic converter and one in every exhaust manifold. Modern vehicles usually have at least four oxygen sensors placed at key points in the exhaust system.
The 3.0L and 3.6L V6 have four oxygen sensors; one in each exhaust manifold, and one just after each catalytic converter.
Code P0420 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.
Do I need to replace all of the sensors at once? It is best to replace O2 sensors in pairs. For example, if you replace the downstream left sensor, you should also replace the downstream right.
Vehicles with dual exhaust have four O2 sensors. This part monitors the amount of oxygen present in the exhaust of your vehicle. Based on this reading, the vehicle`s computer adjusts the fuel-oxygen mixture that is provided for the engine.
An ACDelco GM Original Equipment Oxygen (O2) Sensor is a GM-recommended replacement for your vehicle`s original component, and is a special feedback sensor on your vehicle`s exhaust system. This sensor measures the proportion of oxygen in the exhaust gases.
Most cars have at least two oxygen sensors located throughout the exhaust system; at least one in front of the catalytic converter and one or more downstream from the catalytic converter. The “pre-cat sensor” regulates fuel supply, while the downstream sensor measures the efficiency of the catalytic converter.
4 cylinder engines will have two oxygen sensors.
The oxygen or lambda sensor is one of the most important and one of the most misunderstood components of a modern fuel injection system.
Driving your car with the P0420 code will only lead to further damage to the catalytic converter. Plus, the problem can affect other parts of the car, such as the fuel line and exhaust systems. This is why it`s important to actively monitor your car`s catalytic convertor to avoid other costly repairs.
If you remove the oxygen sensors from your vehicle, you will ruin the efficiency of the engine, thus consuming around 10 to 20 percent more gas than otherwise required, and also cause early failure of many components such as the spark plugs.
The short answer is yes. The air flow to the engine or the manifold pressure is measured to determine the correct amount of fuel to be injected. The oxygen sensor measures the amount of oxygen left after combustion for emissions and also to keep the engine running efficiently.
Poor Engine Performance

Will a bad O2 sensor cause rough idle and loss of engine power? You bet. Moreover, you may also notice poor acceleration, engine misfires, and even stalling. Bad oxygen sensors disrupt all kinds of essential engine functions, including engine timing, combustion intervals, and air-fuel ratio.

Can I Drive My Car With A Bad Oxygen Sensor? We recommend against driving with a bad O2 sensor as the powertrain is not running on the correct fuel mixture. While it may perform fine in the beginning, if your engine is running rich and using too much fuel it might begin to clog the catalytic converter.
The major difference between LSU 4.9 and 4.2 is that LSU 4.9 uses the reference pumping-current, while LSU 4.2 uses the reference air. What does this mean? Basically the reference air can deteriorate while the reference electric signal does not.
MALFUNCTIONING AND FAILED SENSORS Oxygen sensors can fail when the sensor`s ceramic element is exposed to certain types of silicone compounds or when an oil-burning engine leads to the sensor becoming oil-fouled. Also, a small amount of tetra-ethyl lead in the gasoline can kill an oxygen sensor.
Overall, buying an OEM oxygen sensor is a better and safer investment than an aftermarket one. It is less likely to fail, designed to work on your vehicle specifically, and is backed by the manufacturer`s warranty.
A properly functioning oxygen sensor will show a rapidly fluctuating output voltage between approximately 0.1 and 1.0 volts. The time taken for the voltage to change from 0.1 V to 1.0 V (referred to as the lean to rich response time) should be about 300 milliseconds.
While best practice is for the array to contain a mix of sensors selected from differing lots, you should not mix brands or very old sensors with very new sensors.
What the P0137 code means. P0137 is the OBD-II generic code indicating the O2 sensor for bank 1 sensor 2 is failing to increase the voltage output above . 21 volts indicating excessive oxygen in the exhaust.
The O2 sensors are located on the exhaust manifold near the catalytic converter. The manifold receives a mixture of air and fuel from the engine. Since there are two catalytic converters for recent models of cars, there are two oxygen sensors in a car.
The O2 sensor keeps your emissions in check. Your vehicle may have one, two, three or four sensors, depending on the engine type, make and model.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

check engine light O2 sensor already replaced same codes still popping up after replacing old O2 sensor
ANSWER : Hi there. What you received from the parts store was a code retrieval, not a diagnostic. The codes are set when a fault is detected against normal operating parameter. The computer does not know what caused the fault, only that the fault meets the criteria for this code to set. There could be a problem in the wire harness, converter, or the ECM. The code and data are needed to properly assess the direction that a diagnosis needs. I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection.

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O2 sensors changed, but check engine light still showing code after clearing it I checked fuse. Wires are good and used Denso OE.
ANSWER : Depending on what the code was for will determine if the oxygen sensor was to be replaced. If the conditions were for a rich or lean mixture and it said oxygen sensor, then the spark plugs and wires could need replaced if its a rich reading or the fuel injectors could be clogged or not working if its a lean mixture. If the code said that the oxygen sensor was bad, then check the harness and see if there is a break in the wiring or a short to ground in the wiring from the oxygen sensor to the main harness. If you need further assistance with your check engine light being on, then seek out a professional, such as one from Your Mechanic, to help you.

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i need to replace both o2 sensors for vehicle listed above. so is it front left and back left o2 sensors?
ANSWER : Hi there:

Typically when an issue comes up with O2 sensors, it’s either the front bank (before the catalytic converter) or the rear bank (after). It’s very rare that all need to be replaced. However, the quickest and most effective way to determine which is faulty and need to be replaced is to have one of our professional mechanics complete a check engine light is on inspection. This service will allow them to determine which one is bad, and if you’d like, we can replace that O2 sensor for you.

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Diagnostic code read o2 sensor bad, replaced o2 sensor, cleared code but engine light came back on, is it caused by bad air filter
ANSWER : Hello there. Typically jump starting a vehicle doesn’t trigger an OBD-II error code. However, one of the most common misdiagnosis issues with the P-2270 is replacing the O2 sensor before diagnosing if there are any exhaust leaks. Obviously, you’ll want to check for the exhaust leaks first, repair the damaged component, and then clear the codes before scanning the vehicle again. Sometimes the electrical harness attached to the O2 sensor is damaged or dirty which will also trigger this error code. The noise and vibration may be an indicator of a loose exhaust pipe, which may be the source of the error code staying on. If you need any help, have a technician from YourMechanic come to your home or office to diagnose your Check Engine Light and make the necessary repairs.

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So I had two codes come up for two of my o2 sensors..replaced them both and check engine light is still on…my mechanic seems to
ANSWER : Hi there:

Although it’s hard to say if there was serious damage done to your ECM during this service, it’s more likely that the stored error codes were never cleared from the ECM, and that’s why the warning lights still appear. This is a common oversight with some mechanics, but if you have a mobile mechanic complete a check engine light inspection, they should be able to clear those stored codes and determine if further damage has occurred.

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o2 sensor reads 0 volts.
ANSWER : You may need to look at the code P0122 since it pertains to the throttle position sensor and this can affect all the drive symptoms you are having. The O2 sensor readings seem to be normal and you are not getting any O2 sensor codes. Your reading of between .2 and .4 volts shows that the converter is doing its job and you have high O2 in the exhaust flow. This is a common and normal reading. When the catalyst is new you may not see the O2 sensor go above .45 volts but as a catalyst ages the sensor will switch more often above the .45 volts until it cannot clean the exhaust anymore. I’d suggest getting some help with a certified technician, such as one from YourMechanic, they will help you diagnose your Check Engine Light further and help you fix it accordingly.

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Check engine light – O2 sensor circuit + speed sensor circuit…
ANSWER : Hi there. O2 sensor low voltage can be caused my a number of things. Mass air flow sensor was only one of them. It can be a bad O2 sensor, coolant temperature sensor, or wiring issue.

What should be done is a proper diagnosis for the Check Engine Light. Using a complete scanner rather than just a code reader gives a technician the opportunity to not only read trouble codes, but to read voltages for individual sensors. While a code reader tells you the relevant system that set the Check Engine Light on, but with a number of possible causes, the full scan tool allows checking of each individual cause. Having a proper diagnosis will help you have this repaired correctly without replacing parts that are not faulty.

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Car won’t accelerate past 25 mph and makes deep noise when you try too replaced o2 sensor maf sensor/ throttle body does rattle
ANSWER : Hi there. It is quite possible that your car has entered what we call a fail safe or "limp mode" due to an error code being activated and stored in the ECU. This will occur when the ECU or a sensor detects a mechanical or electrical fault on one or several fuel, ignition, cooling or powertrain systems. It’s designed to allow you to safely "limp" your car to a repair facility or home so a professional mobile mechanic can complete a car is slow to accelerate inspection and determine the right course of action. It is also possible that this issue is caused by a loose vacuum line or other component like the throttle position sensor.

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