The most popular lambda sensor failure symptoms

Did your car unexpectedly start using too much fuel, resulting in a decrease in engine power? Or worse, black smoke is coming out of the exhaust? These could be lambda sensor damage symptoms. The malfunction of this component can have a disastrous effect on the performance of other parts of the exhaust system. Where is the lambda sensor located? How do I check whether the lambda probe is in working order? What are the causes and consequences of its damage?


What is a lambda sensor?

The lambda sensor is a small part of the exhaust system of any modern car. Inconspicuous, but performing an important function in the process of cleaning the exhaust gases emitted by gasoline and diesel engines. It has been in use since 1979. Today, almost every car has two probes. The alternative name of the lambda probe is oxygen sensor.

A lambda sensor is a detector located in the exhaust system between the engine and the catalytic converter. The most popular zirconium oxygen sensors contain a solid electrolyte, which is the basic measuring part. This element is covered by two platinum plates that serve as the exhaust catalyst. One plate is in direct contact with the exhaust gas, and the other with air from the atmosphere. A ceramic housing made of zirconium dioxide is designed to protect the entire element from contaminants. Inside the sensor, there is also a special heater.

Although on the surface it seems like an element with a complicated structure, everything will become clear once you know what it is used for - the lambda sensor is responsible for maintaining the correct mixture of fuel and air, burned in the cylinders of the engine. To maintain the correct parameters, there should be 14.7 times more air than fuel. If the sensor detects an incorrect ratio, it sends such information via a wire to the engine control module. It corrects the composition of the mixture, thus minimizing fuel consumption and reducing the discharge of greenhouse gases from the exhaust system.


What causes lambda sensor failure?

Due to its function, the sensor is exposed to constant stress. Its outer part is exposed to large temperature changes and mechanical damage. When water or oil particles enter the exhaust system, unfortunately, the lambda sensor will almost certainly be damaged. Sometimes the wires can also become stressed, and they can break or rub together. Oxygen sensor damage sometimes results from poor fuel quality. Especially low-octane, contaminated or lead-containing fuel can be destructive to the lambda sensor.


These are typical lambda sensor failure symptoms

When driving your car, you may experience problems caused by a defective lambda sensor. However, the symptoms of the malfunction are quite characteristic and will help to locate the deficiency quickly. If the sensor malfunctions, the following signs will appear: 

- check engine light will come on;

- fuel consumption will increase dramatically (even by half!);

- the engine will have less power; 

- spontaneous changes in engine speed will occur;

- black smoke will come out of the exhaust. 


Remember that the check engine light can also inform you about problems with other components and is rather a general signal, letting you know about the damage that has occurred. The moment you notice other disturbing harbingers in addition to the light on, you may suspect damage to the lambda sensor. Symptoms of a damaged lambda sensor are a signal to hand your car over to a trusted mechanic for inspection. Don't ignore the problem because a broken lambda sensor entails other, more serious malfunctions.


How do you check the lambda sensor in your car?

Checking the lambda sensor should be a regular activity, performed by your mechanic. If you suspect a malfunction, you can inspect the oxygen sensor yourself. Try one of three ways:

- verify the errors stored in the on-board computer with a diagnostic tester,

- remove the sensor and conduct a thorough visual inspection of its condition,

- use a lambda sensor diagnostic tester.

The first way will help indicate what exactly is malfunctioning - the sensor, the heater or perhaps the electrical system? The second will allow you to see if the lambda sensor is covered with tarnish. White or red color indicates poor-quality fuel, black is a sign of high oil consumption, and greenish color is a harbinger of coolant entering the combustion chamber, which is caused by the failure of the head gasket. The sensor may also be covered with a brownish tinge, which should direct your attention to the operation of the injection system. 

The last way requires minimal knowledge of the correct parameters, but you will determine with it whether the problem is a defective lambda sensor. How do I check its parameters? To begin with, you need to evaluate the reference voltage on the sensor's connection plug.It should be between 400 and 500 mV. By the way, make sure you know the frequency of the signal. At idle, it should have a value of about 0.5 Hz. You also cannot forget about the voltage of the sensor, the resistance, and the voltage of the heater. If everything is fine, then the abnormalities must be due to damage to another car part.


Can you drive with a faulty lambda sensor?

A malfunctioning lambda sensor results in an improper air-fuel mixture ratio. An excessively lean mixture contributes to a decrease in engine power, while an excessively rich mixture results in the destruction of the catalytic converter. If a damaged lambda sensor is used for too long, it will lead to further defects in the exhaust system. 


Will a faulty lambda sensor fail technical inspection?

The most common malfunction caused by a non-functioning lambda may be overheating of the combustion system. Driving with a faulty lambda sensor leads to gradual damage to the active layer of the catalytic converter, and eventually to its complete destruction. A car with a faulty oxygen sensor does not meet the standards for clean exhaust gases, so this failure should be repaired before the technical inspection of the car.