Lambda sensors and NOx sensors

How can a lambda sensor become defective and what are the symptoms?

For a lambda sensor to work correctly, it must be at operating temperature. This is done with the hot exhaust gases. If the engine is still warming up, a heating element in the control sensor takes over the heating in newer vehicles. Only from a temperature of over 350°C, a control probe can make correct evaluations. This is precisely the first sticking point. If only short distances are driven, most of the heating power must be provided by the heating element. However, this is not designed for continuous power and can become defective if the load is too high.

The lambda sensor also becomes dirty over time, as the pollutants in the exhaust gases are deposited on it. This means that the control sensor can no longer measure correctly. If, for example, engine oil enters the combustion chamber due to damage to the cylinder head gasket or defective piston rings, and residues of this oil subsequently end up in the exhaust gases, this can also clog the lambda sensor upstream of the catalytic converter. Excessive exhaust gas temperatures above 950°C due to combustion malfunctions and the use of leaded fuel also cause faster wear. In addition, incorrect cleaning of the control sensor can poison the reference air, which also means that correct measurement can no longer be carried out. For this reason, a lambda sensor must not be cleaned with contact spray before the catalytic converter.

A defective lambda sensor can cause the following symptoms:

The engine power decreases
Increased fuel consumption occurs
The exhaust gases turn dark
The check engine light comes on

These symptoms do not always mean that the lambda sensor is defective. This can also be due to other causes. Therefore, the fault memory should be read out first. An additional visual inspection is also useful, because like spark plugs, lambda sensors have different wear profiles. A lambda sensor tester can also confirm whether the lambda sensor is really defective. Only then is it worth considering replacement. The diagnostic sensor, i.e. the lambda sensor after the catalytic converter, is usually less affected by wear. To be on the safe side, however, this should also be checked so that the wrong one is not accidentally replaced and the fault persists.

What to consider when buying a lambda sensor?

It is important before buying a lambda sensor to clarify at which point it should be replaced. Position 1 describes the lambda sensor before the cat (control probe), position 2 the lambda sensor after the cat (diagnostic probe). In addition, it can also be distinguished whether it is heated or unheated. In older vehicles, only unheated control probes are used, since the exhaust system there is not yet sufficiently developed. In addition, the number of lines and the type of connector connections differ for each vehicle, as does the length of the cable.

Therefore, if you want to buy a lambda sensor, it is recommended to first select the vehicle. Then the products are reduced to only suitable results. With the remaining offers can be selected from various well-known brand manufacturers. We carry high-quality spare parts from the following brand manufacturers:

Bosch
Delphi
FAE
Febi Bilstein
Herth+Buss
NGK
Trucktec Automotive

They are all characterized by a high level of know-how and use only high-quality materials. Their products meet all the requirements of the vehicle manufacturer and can therefore be used without hesitation.

In addition to lambda sensors, this category also includes NOx sensors. NOx sensors function in a similar way to lambda sensors, except that they measure the proportion of nitrogen oxides rather than the oxygen content. Generally, NOx sensors are used in addition to the lambda sensor and are predominantly used in diesel engines. Their measurement is used, for example, to control the proportion of diesel additives such as AdBlue.

If you are unsure which NOx sensor or lambda sensor to purchase, please feel free to contact our customer service with the 17-digit chassis number.

Top Brands

The brand manufacturers at a glance

What is a lambda sensor and how does it work?

How can a lambda sensor become defective and what are the symptoms?

What to consider when buying a lambda sensor?