Ecological control of the car

Mal Spool, yes roads — a proverb, as it is impossible, a better characterizing the role of an oxygen sensor in a modern motor vehicle device. With all the compactness of the size, it performs an extremely important feature for the control of emissions of harmful substances and ensuring efficient engine operation. Therefore, over 40 years of its existence, oxygen sensors have become an essential component of the engine control system.

Oxygen sensors (also called lambda probes) help control the fuel consumption of the car, which helps to reduce the volume of harmful emissions. The sensor continuously measures the volume of unburned oxygen in the exhaust gases and transmits this data to the electronic control unit (ECU). Based on these data, the ECU regulates the ratio of fuel and air in the fuel-air mixture entering the engine, which helps the catalytic neutralizer (catalyst) to work more efficiently and reduce the amount of harmful particles in exhaust gases.

As explained

Types of sensors

Today in vehicles used sensors of three main types. In the most modern cars that meet the european standards of Euro 5 and Euro 6, most often equipped with turbocharged engines with small volume engines, but highly functional, as a regulatory, that is, the first sensor installed in front of the catalytic neutralizer, so-called broadband sensors are used — Air Fuel Ratio controlling the ratio of «fuel-air».

The control sensor directly affects the operation of the engine having an injection system. In such engines, all processes are monitored by an electronic control unit. And just an oxygen sensor in the composition of the exhaust gases allows the electronic unit to understand which way to shift the ignition angle in order for the mixture to burn more fully, and the engine, as a result, worked as efficiently as possible and eco.

Andrei Rybkin, Technical Specialist, «NGK SPARK PLAGS Eurasia»:



The third type — titanium sensors — largely similar to zirconium sensors, but atmospheric air is not required to work to work. Another difference of titanium sensors from others is the signal transmitted by them, which depends on the electrical resistance of the titanium element, and not from the voltage or current of the current. Taking into account these features, titanium sensors can be replaced only similar, and other types of lambda probes cannot be used.

Error signal

Oxygen sensors are essential sensors in the engine control system, as they allow the ECU to control the composition of the fuel-air mixture. The sensor failure means that the engine control system does not receive feedback in the form of information on the oxygen concentration in the exhaust gases. This forces the system to control the engine along the open circuit, based on the estimated values of the parameters, which leads to a decrease in efficiency and increase the level of emissions of harmful substances.


Thus, the ECU uses signals from both the regulatory and diagnostic sensor, and with their help ensures optimal engine operation mode.

At the same time, when the computer generates an oxygen sensor error, it is important to understand that not always this error indicates a malfunction of the sensor itself. Quite often, it is associated with incorrect mixing formation, and therefore the problem should be signed not in the sensor, but in the corresponding engine systems.

However, it will never be superfluous to carry out the primary diagnosis of the sensor: the zirconium sensors without much difficulty can quickly check their heater chain.

Andrei Rybkin:



That is, we look at the wiring, we find two identical wires, we measure resistance on them and process with reference literature. The somewhat of the resistance: 4.5 ohms, 6 ohms and 13 ohms. If the indicator is very different — more than 1-1.5 ohms — the sensor should be replaced.

Andrei Rybkin:



Experienced experts assure: one of the most common mistakes associated with the replacement of the oxygen sensor is incorrect selection. Sensors, unlike many other auto components, even on the same vehicle models may differ, for example, depending on the market of its sales.

Andrei Rybkin:

To avoid such confusion, it is necessary to select sensors strictly by directory, preferably on its VIN, especially when it comes to a rather rare model / modification. And having received the original article, take advantage of the sacrings on the After-Market spare parts.

In the assortment of many premium suppliers are also the so-called universal sensors that do not have the connector and use part of the wiring from the old sensor.


Universal sensors are naturally cheaper, it will, for example, a more budget solution. As a rule, in the catalogs, together with a special sensor, the universal is always specified if it is possible to install such a sensor.

Andrei Rybkin:

That’s how we smoothly approached the replacement and installation of the sensor.

Replacement and installation

The replacement of oxygen sensors does not cause serious difficulties, but you should always strictly adhere to several elementary rules.

First, when tightening oxygen sensors, as when fixing many other auto components, it is necessary to observe the prescribed tightening moments, because when the sensor is drawdken, the risk of damage is significantly increasing.

Secondly, one of the most frequent breakdowns of oxygen sensors is due to the oil in the wiring. Moreover, often the oil can flow fairly exotic ways. For example, from a non-grid oil pressure sensor in the cylinder block.

Andrei Rybkin:

Therefore, before replacing the oxygen sensor, carefully inspect it. If you see that dust with dust connector, there is an oil flaw — it is an unambiguous evidence of the presence of oil. Therefore, it is necessary to urgently check how it turned out here. Otherwise, even a new sensor will quickly fail, and such a breakdown will not be considered as a warranty case, since it led to the external impact, and not a constructive defect. So look for leakage.

A special case, if you can express it, the «replacement» of the oxygen sensor is associated with its full elimination from the system for one reason or another. This is still on the market, so we consider it expedient to give a few comments about this.

So, the regulating sensor can never be deleted, because its testimony is guided by the ECU to ensure the correct operation of the engine. The second sensors (standing after the neutralizer) can dismantle as it were for nonsense, but in fact they, as we have already noted, fully control the work of the neutralizer itself.

If an error occurs to physically remove the sensor, the engine will switch to the alarm mode, but through all sorts of software manipulations in the control unit, the signal is turned off from this sensor and the engine thinks that it is in principle. Naturally, such an engine will never correspond to the environmental standards for which it is designed.

But this is not the worst thing. The worst thing is that it is absolutely incomprehensible, which effect is given to the applied software and how their use will affect the mixture formation. Very often, such a correction of the ECU leads to the fact that the engine is configured to a completely non-optimal mode of operation with power loss and high fuel consumption.

However, it should always be remembered that the situation can be played back. The factory firmware of the control unit is known, and the mechanically the sensor is not difficult to return to the place.

Life time

Sensors, in contrast to, allow, spark plugs or the more filters are not a consumable component. They do not change to achieve a certain period, but only depending on the state. On average, according to experts, if the engine is working, if there are no external problems and fuel is quite satisfactory, then more than 100 thousand km run sensors go calmly.

Andrei Rybkin:



A business

We cannot predict what tasks will be prioritized for the segment of automotive components. However, we are confident that in the process of technology development and changes in legislation, oxygen sensors will continue to play a crucial role in the engine design.