News

Nov 18, 2023

Exhaust

Nowadays, different sensors installed at the exhaust tract of modern passenger

Nowadays, different sensors installed at the exhaust tract of modern passenger cars and commercial vehicles monitor the exhaust-gas composition with top precision

Nowadays, different sensors installed at the exhaust tract of modern passenger cars and commercial vehicles monitor the exhaust-gas composition with top precision. In this way, they make an important contribution to compliance with legal emission limits and the regulations concerning on-board diagnoses. Replacing defective and worn sensors is thus of major importance. Besides lambda sensors, particle sensors and differential-pressure sensors, the Bosch range has now also been complemented by exhaust-gas temperature sensors and – brand new – nitrogen-oxide sensors for most of the vehicles on the European market. Combining these sensors with the Denoxtronic exhaust-gas treatment system, workshops are provided with a comprehensive range of the exhaust-gas treatment components featuring OE quality.

Bosch builds on decades of experience in sensor technologies. Lambda sensors, for instance, are used to measure and optimize the air/fuel mixture of gasoline and diesel engines – and they were invented by Bosch. Bosch was a first-minute pioneer in terms of particle sensors monitoring diesel particle filters, as well. And Bosch also supplies vehicle manufacturers worldwide with large numbers of all exhaust-gas sensors.

Five exhaust-gas sensors help complying with the emission limits

Reliable analysis of the exhaust-gas composition is the basis for efficient exhaust-gas treatment. For this purpose, modern cars and commercial vehicles are equipped with different sensors installed into the exhaust duct. All of these sensors are integrated into the on-board diagnostic system and can easily be identified and checked using a diagnostic tester such as, for instance, a Bosch KTS in cause of any faults. If defective, Bosch sensors can be replaced both easily and quickly.

Nitrogen-oxide sensors

More and more diesel cars and a growing number of light and heavy commercial vehicles are equipped with nitrogen-oxide sensors. By means of a particularly resilient and heat-resistant ceramic sensor element, these sensors measure the amount of nitrogen oxide (NOx) downstream of the SCR catalytic converter. Some engine types include a second nitrogen-oxide sensor upstream of the catalytic converter. These sensors control the amount of urea (AdBlue) injected into catalytic converter for the selective catalytic reduction (SCR) in order to reduce the NOx emissions. In addition, they also monitor the SCR components. As SCR technology is used more frequently, nitrogen-oxide sensors are also of increasing importance for the aftermarket and workshop business. The current Bosch range comprises 24 part numbers including the matching sensors for several vehicles. And yet, the range is continuously expanded.

Exhaust-gas temperature sensors

Exhaust-gas temperature sensors can be installed at different locations within the exhaust duct of diesel and gasoline engines. They measure the temperature of exhaust gases and send an electric voltage signal to the engine control unit. Used in diesel engines, exhaust-gas temperature sensors monitor the temperature of the particle filter. Therefore, they significantly contribute to compliance with emission limit values and fuel efficiency. Used in gasoline engines, exhaust-gas temperature sensors are used to protect critical components such as e.g. Catalytic converters and turbochargers. Since July 2020, the Bosch aftermarket range for workshops comprises some 90 part numbers covering most of the vehicles of European car makers.

Particle sensors

Since 2019 already, workshops can order particle sensors at Bosch. The range comprising 40 part numbers is continuously expanded. Particle sensors analyze the amount of soot particle contained in diesel emissions by means of resistance measurement. Based on the values thus obtained, the control unit analyzes the functionality of the diesel particle filter. Prior to each measurement, the sensor element is regenerated by heating it up in order to keep the sensor in the same condition for all measurements.

Differential-pressure sensors

Differential-pressure sensors measure the pressure difference of the particle sensor: The values measured provide information on the condition of the particle filter in order to trigger the demand-based and fuel-saving particle-filter regeneration – so-called selfcleaning or burning clean. Differential-pressure sensors are also used to control low-pressure exhaust-gas recirculation. The current Bosch range comprising more than 40 part numbers for these sensors covers most of the vehicles on the European market.

Lambda sensors

Lambda sensors determine the amount of oxygen contained in exhaust gases. Based on this value, the engine control unit determines the optimum fuel quantity to be injected into the combustion chamber. Lambda sensors are used in gasoline, diesel and gas engines. The Bosch range of lambda sensors includes a matching lambda sensor for more than 80 percent of all vehicles on the market. With their high measurement accuracy, these sensors actively support engine efficiency and effective exhaust-gas treatment. Compared to worn lambda sensors, new lambda sensors allow fuel savings of up to 15 percent.

Denoxtronic

The Denoxtronic exhaust-gas treatment system is also of increasing importance. Increasingly used in diesel-powered vehicles, it generates additional potentials for automotive workshops. This system injects a watery urea solution (known as AdBlue) into the exhaust duct. In combination with the SCR catalytic converter, this allows turning harmful nitrogen oxides (NOx) into water and nitrogen. As Denoxtronic system developer, Bosch provides comprehensive solutions for workshops – reaching from diagnoses and spare parts through to repairs and technical trainings.

SOURCE: Bosch