How To Test O2 Sensor With 4 Wires+ 4 Wire Oxygen Sensor Diagram

Last updated on June 28th, 2023 at 05:16 pm

Are you wondering how to test o2 sensors with multimeter? Well, this post on how to test a 4 wire O2 sensor with a multimeter will be your guide as I show you a 4 wire o2 sensor wiring diagram how to test it yourself and many more.

The current computerized engine control systems require inputs from a lot of sensors to regulate how the emissions system, engine, and other vital components of your car perform. It is the function of the O2 sensors (oxygen sensor) to give accurate information to your car computer to avoid driving issues, emission failures, and increased fuel consumption.

This makes the oxygen sensor one of the most vital sensors in a vehicle. Sometimes it is known as the “O2” sensor. It works like a generator that produces its voltage whenever it gets hot.

How To Tell Which O2 Sensor Is Bad + 4 wire o2 sensor wiring diagram

Knowing which of the upstream or downstream oxygen sensors is going bad is the same as understanding which O2 sensor is bad. In case your mileage is going bad, this simply means your fuel trims are putting in lots of gas and haven’t been updated in a while. However, the upstream is usually the issue here.

More than 95% of the time, the oxygen sensors are being changed by using diagnostic trouble codes (DTCs). The diagnostic trouble codes are good for identifying which of the sensor is malfunctioning. This means that both DTC descriptions and real-time data are displayed, and the code reader will be indicating B1S1 (bank 1, sensor 1, which is upstream), B1S2 (downstream), B2S1, and B2S2.

It will be the duty of the technician to make use of a scope to directly test the heater circuit current or the resistance to measure sensor voltage output.

Using Voltmeter or OBD2 Scan Tool to test: You can know which oxygen Sensor is bad by making use of the OBD2 Scan tool. To do this, test the O2 sensor using an OBD2 scan tool or a voltmeter to check the voltage and the time of its reaction. A perfectly working front (upstream) O2 sensor 1 will normally flip from rich to lean while at a fairly regulated rate, which should result in a wavelike shape.

You will notice that the voltage that will be gotten by the oxygen sensor should range between 0.1 and 0.9 volts. The 0.9 volts will be on the rich side and 0.1 volts will be on the lean side.

This simply means that once your measurements fall within this range, it shows that the O2 sensor is in perfect condition.

Note that the back (downstream) oxygen sensor 2 is meant to be a catalyst monitor, which should be hanging around half a volt once everything is properly working. However, this dimension will vary depending on the manufacturer.

What Causes An Oxygen Sensor To Fail

Many things could cause the oxygen sensor to fail. A lot of times the O2 sensor gets contaminated and clogged because of byproducts of fuel.

Whenever a sensor fails, it won’t provide accurate data to the ECU, and this will cause lots of issues to the car. Below are several reasons that could cause the oxygen sensor to completely fail.

1. Long usage

Long usage happens to be one of the most common reasons that cause the O2 sensor to fail. The oxygen sensor’s lifespan should be 3 to 5 years or 60,000 to 90,000 miles.

Just like every other component in the vehicle wears out, that’s how the oxygen sensor also wears out over time. This can affect the oxygen sensor’s responses to the car and can result in the total failure of the sensor.

2. Contamination

Another big reason that causes the oxygen sensor to fail is contamination. As you may know, the O2 sensor can be contaminated sometimes with lots of fuel byproducts like sulfur, lead, and fuel additives.

Most of this contamination of byproducts prevents the sensor from sending an accurate signal to the ECU, and due to this, the oxygen sensor can go bad.

3. Too much Temperature

Having too much temperature in the exhaust gases can cause the oxygen sensor to fail. Normally, the Oxygen sensor is always exposed to high exhaust gas temperatures, and this kills it quicker.

Too much temperature can quickly minimize the oxygen sensor’s lifespan, and this can make the O2 sensor fail.

4. Irregular Maintenance

If you intend to make your car work perfectly, then you have to take care of it by going for regular inspection.

When you skip maintenance regularly, it can speed up the failure of your oxygen sensor. When your air filter is dirty and the spark plug is fouled, it can increase the failure rate of the oxygen sensor and causes it to completely fail.

5. Making use of Low-Quality Gas

Another big cause of bad oxygen sensors is using low-quality gas. When you use a fuel not recommended, it can cause the O2 sensor to fail quickly. A low-quality gas can produce more lead, sulfur, and oil ashes in the engine, and this can make the oxygen sensor fail.

6. A Leaking Gasket

Another thing that can also cause the oxygen sensor to fail is a leaky gasket. A leaking head gasket can produce silicate, and this can block the oxygen sensor making it not produce the right voltage, which can cause it to fail.

7. A Worn-Out Piston Rings

When you have a worn-out piston ring, it can cause an oxygen sensor to fail. A worn-out piston ring, having cracks in the cylinder block, valve guides, and the combustion chamber can produce harmful phosphorous from the engine oil, and this can cause the oxygen sensor to fail.

Overview On 4 Wire Oxygen Sensor Diagram

Every vehicle engine comes with lots of complex set of systems that are monitored by many kinds of sensors. However, the 4 wire universal oxygen sensor happens to be one of the sensors that help in monitoring fuel consumption. The 4 wire universal oxygen sensor helps in measuring the amount of unburned oxygen which is present as it exits your vehicle, and this is indicative of the fuel mixture. You have to be aware that this 4 wire universal oxygen sensor requires replacement every 60,000 miles and also needs a specific wiring process.

One of the wires is used for signal purposes, one other wire is for ground. Then two other wires are used for the heater which makes the oxygen sensor be heated electronically.

how to test o2 sensor with 4 wires to 1 wire + Tools Needed for Testing gm 4-wire o2 Sensor

when testing an oxygen sensor with one or more wires you will need to get some tools. below are needed tools for testing various kinds of oxygen sensors, including testing the gm 4-wire o2 sensor.

Tools Needed For Testing GM 4-Wire O2 Sensor

Digital Voltmeter Testing
Multimeter See this One on Amazon)

How To Test 4 Wire O2 Sensor With A Multimeter

The 02 sensor with 4 wires happens to be the most commonly used oxygen sensor in your engine. Two of the wires are meant to be the heated circuit while the other two wires are meant for sensing elements. Both work by producing their voltage as they get hot.

How to test Oxygen Sensor’s Heater Wires

The first thing to do is to check the oxygen sensor’s heater wires to know if the heating wires are broken. Just follow the method below:

Start by switching the Digital Multimeter you have to the Ohmmeter mode.
Then back probe the ground wire of the 02-sensor heater’s hot.
You have now connected the multimeter red lead to the heater hot wire.
Then connect the multimeter black lead to the heater ground wire.
In case the heater wires of the O2 Sensor in your car are working well, the readings you will see on the Digital Multimeter should have some value between 10 Ohms to 20 Ohms.

Make sure the engine of your car is switched off before the test is carried out.

How to test Oxygen Sensor’s Signal Wires

Make sure you turn off your engine and allow the car to cool.

Then switch the Digital MultiMeter to the voltmeter mode.
Now back probe the O2 sensor’s signal voltage and the ground wire.
You need to connect the Digital MultiMeter black lead to the back probed ground signal wire.
Just connect the Digital Multimeter red lead to the signal voltage wire.
You need to turn on the engine of your car.
After that, the voltmeter will show you the reading which should look like 0.1 to 0.9 volts once the sensor wires of the car are working properly.

What Is 4 Wire O2 Sensor Resistance?

All vehicle engine comes with systems that are being monitored by various sensors. This means that the 4 wire O2 sensor resistance happens to be one of the sensors that help to monitor the consumption of fuel.

One of the wires is used for signal, one other wire is for ground. Then two other wires are meant for the heater which makes the O2 sensor to be heated.

How To Test O2 Sensor Wiring Harness

How to test 1 wire oxygen sensors:

Since this type of oxygen sensor generates more electrical current after it reaches its operating temperature, it makes it one of the easiest to test. The engine’s control computer system reads the current and makes the required changes to the fuel mixture.

How to test 2 wire oxygen sensor

Any oxygen sensor that comes with two wires must have a heating element to make sure the O2 sensor begins working immediately instead of waiting to get heated via exhaust temperature.

This 2 wire oxygen sensor, one of the wires is meant for signal, and the second wire is a constant 12-volt signal which comes from the engine control computer system. Note that this 12-volt current which is constant is used to heat the heating element via the O2 sensor, while the oxygen sensor casing is used as a ground meant for the heating element.

How to test a 3 wire Oxygen sensor:

The two-wire and 3 wire designs are similar; the only difference is that instead of making use of the O2 sensor body as a ground, the 3 wires will be the ground. This will help to eliminate the potential of poor ground between the oxygen sensor and the exhaust system which should make it more efficient.

How to test a 4 wire oxygen sensor:

Here comes the type of sensor that outperforms every other. This is because it has a constant twelve-volt signal and a constant ground for the heating element which comes from the engine control computer system. The reason for this is to allow the signal to be more correct, instead of waiting for the oxygen sensor to produce its current.

How To Test O2 Sensors With A Multimeter

One of the easiest tests to do on the O2 sensor is using a multimeter. this is to be enquired if the heating element is broken. You can examine the O2 sensor’s heating element by doing the following:

Turn on the multimeter to resistance mode.
Then connect the testing leads to the heater power and the ground connector wires or pins.
Now read the multimeter measurement. When cold, most of the heaters will have an internal resistance of around 10Ω to 20Ω.
One other type of test you can run on a self-heated O2 sensor is to observe if the heating element is being powered. For you to carry out this test:
Ensure your engine exhaust system is cold. This is because some heaters won’t turn on if the engine exhaust pipe is hot.
Then turn the multimeter on, to ‘DC voltage’ mode.
You can now connect the multimeter to the heater’s power wires or via the contacts.
Then turn on the engine.
Examine the voltage reading you’ll see on the multimeter, you’ll notice it’s between 12V and 14V.

What Are O2 Sensor Wiring Color Codes?

TOYOTA wire 1 is black, wire 2 is blue and black, wire 3 is blue, black, and white, and wire 4 is white, blue, and black.

MAZDA wire 1 is blue, wire 2 is black, white, wire 3 is black, white, and blue, and wire 4 is brown, blue, white, and black

NISSAN wire 1 is green, black, wire 2 is brown, black, and blue, wire 3 is green, blue, and brown, and wire 4 is black, white, and blue

FORD wire 1 is black, wire 2 is blue and gray, wire 3 is black, gray, and white, and wire 4 is gray, blue, and black.

BMW wire 1 is purple, wire 2 is black and gray, wire 3 is black, blue, and purple, and wire 4 is gray, white, black, and blue.

BENZ wire 1 is white, wire 2 is black, wire 3 is gray and black, and wire 4 is green and white

Final though on Post on how to test o2 sensor with 4 wires+ 1, 2,3 4 wire oxygen sensor diagram

As you can see the oxygen sensor is what lets the computer know if the fuel mixture is burning rich (not enough oxygen) or lean (too much oxygen).

It’s very important to know the ratio of fuel to air because it allows the vehicle’s engine to make necessary adjustments to make sure that the vehicle runs perfectly well.

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