What is a Nox Sensor and How Does Its Failure Affect Your Vehicle?

A nox sensor monitors the levels of nitrogen oxide in the exhaust. If the sensor detects that the levels are too high, it will send a signal to the engine control unit to adjust the air-fuel mixture accordingly. If the nox sensor fails, it will cause the engine to run lean, which can lead to engine damage.

If your car’s NOx sensor fails, it could mean big trouble for your engine. NOx sensors are responsible for detecting levels of nitrogen oxides in the exhaust gas and then sending a signal to the engine control unit (ECU) to adjust the air/fuel mixture accordingly. If the sensor is not working properly, it can cause the engine to run too lean or too rich, which can lead to engine damage.

In some cases, a failed NOx sensor can also cause the check engine light to come on.

Diesel Truck Life Aftertreatment Problems Nox Sensor

What Causes a Nox Sensor to Go Out?

The main function of a NOx sensor is to monitor the level of nitrogen oxides in the exhaust gas. If the level of NOx gets too high, it can cause problems with the catalytic converter and eventually damage the engine. There are several things that can cause a NOx sensor to go out:

1. Sulfur deposits on the sensor: Sulfur dioxide (SO2) in the exhaust gas can coat the surface of the NOx sensor, preventing it from accurately measuring the level of NOx. This is more likely to happen if you use fuel that contains sulfur. 2. Lead deposits on the sensor: Like sulfur, lead can also deposit on the surface of the NOx sensor and prevent it from working properly.

This is more likely to happen if you use leaded gasoline. 3. Damage to wiring or connectors: The wires that connect the NOx sensor to your car’s computer can become damaged or disconnected, preventing the signal from getting through. This can be caused by physical damage (like a rodent chewing on them) or corrosion from exposure to water or other chemicals.

4. Faulty sensor: Sometimes, there may be something wrong with the actual sensor itself. It could be a manufacturing defect or simply wear and tear from age and use.

Will a Nox Sensor Derate a Truck?

A NOx sensor derate is when the truck’s computer senses that the NOx (nitrogen oxide) emissions from the engine are too high. The computer then reduces the amount of fuel going to the engine, which in turn lowers the power output and mileage. A truck can be derated for a number of reasons, including:

-The truck’s engine is dirty and needs to be cleaned. -The truck has been driven hard and needs a break. -The ambient air temperature is too cold or hot for the NOx sensor.

Derating a truck will lower its fuel economy and power output, so it is not something that should be done lightly. If you think your truck may need a NOx sensor derate, take it to a qualified mechanic or dealer for diagnosis and repairs.

Can a Nox Sensor Cause Loss of Power?

A NOx sensor is a device that measures the amount of nitrogen oxide in the exhaust gas of an internal combustion engine. The sensor is usually located near the catalytic converter. A NOx sensor can cause loss of power if it becomes clogged or damaged.

When this happens, the engine will run leaner and produce less power.

What Does a Nox Sensor Do on a Diesel?

The NOx (nitrogen oxide) sensor on a diesel engine is responsible for measuring the level of NOx in the exhaust gas. This information is used by the engine control unit (ECU) to adjust the air/fuel mixture and timing to reduce emissions of NOx.

What Happens When a Nox Sensor Fails

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Nox Sensor Failure Causes

If you have a car made in the last few years, it’s likely that it has a NOx sensor. These sensors are designed to measure the amount of nitrogen oxide in the exhaust gas and help the engine adjust its air-to-fuel mixture accordingly. Unfortunately, these sensors can fail, and when they do, it can cause some serious problems.

The most common symptom of a failed NOx sensor is an illuminated check engine light. Other symptoms can include poor fuel economy, increased emissions, and decreased performance. If your NOx sensor fails, it’s important to get it fixed as soon as possible because continuing to drive with a failed sensor can damage your catalytic converter.

There are several reasons why a NOx sensor might fail. The most common reason is simply age or mileage; over time, the delicate sensing element can become damaged or corroded. Another common reason for failure is contamination; if your exhaust gas contains too much soot or other debris, it can coat the sensing element and prevent it from accurately measuring the NOx levels.

Finally, a sudden drop in voltage (from disconnecting the battery or jump starting the car) can also damage the sensor. If you suspect that your NOx sensor has failed, the best thing to do is take your car to a qualified mechanic for diagnosis and repair. In most cases, replacing the faulty sensor will solve the problem.

How to Test a Nox Sensor With a Multimeter

A NOx (nitrogen oxide) sensor is a key component of your car’s emissions control system, and helps to keep your car running cleanly and efficiently. If your check engine light is on, or you suspect that your NOx sensor may be failing, you can test it with a multimeter. To test the NOx sensor, first locate it in the exhaust system.

It will be mounted near the catalytic converter. Once you have found it, disconnect the electrical connector and unscrew the sensor from its mount. Next, set your multimeter to the resistance setting and touch the probes to the terminals on the sensor.

The meter should read between 0.5 and 1 ohms if the sensor is working properly. If not, replace the sensor with a new one.

Nox Sensor Lifespan

Nox sensors are designed to last the lifetime of your car. However, over time and with extended use, they may eventually need to be replaced. There are a few things that can shorten the lifespan of your nox sensor, such as:

• Sulfur deposits from fuel can build up on the sensor, causing it to fail. • The sensor can be damaged by engine coolant or oil leaks. • If the engine is running lean (too much air and not enough fuel), it can damage the nox sensor.

If you think your nox sensor might be failing, it’s important to get it checked out by a professional as soon as possible. A faulty nox sensor can cause your car to emit higher levels of emissions, which could lead to failed emissions tests or even legal penalties.


A Nox sensor is used in cars to monitor the level of nitrogen oxide emissions. If the sensor fails, it can cause the car to emit too much pollution. This can damage the environment and also cause health problems for people who breathe in the emissions.

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