What is the difference between oxygen sensor and nitrogen oxide sensor?

Both oxygen sensor and nitrogen oxide sensor are very important sensors in automobile exhaust emission system. They play a key role in monitoring and controlling engine emissions, but there are obvious differences between the two.

Oxygen sensor

Main function: Monitor the oxygen concentration in engine exhaust, so as to control the air-fuel ratio, ensure efficient combustion of the engine and reduce harmful gas emissions.

Working principle: Use the migration of oxygen ions in solid electrolyte to generate electrical signals, the size of which is proportional to the oxygen concentration.

Type:

Narrowband oxygen sensor: Mainly used for closed-loop control, it can only detect the state of too rich or too lean mixture.

Wideband oxygen sensor: It can continuously monitor the air-fuel ratio of the mixture from rich to lean, and achieve more precise control.

Location: Usually installed between the engine exhaust manifold and the catalytic converter.

Nitrogen oxide sensor

Main function: Detect the concentration of nitrogen oxides (NOx) in engine exhaust and provide feedback signals for the selective catalytic reduction (SCR) system to reduce NOx emissions.

Working principle: Using electrochemical principles, by measuring the current size, the NOx content in automobile exhaust can be accurately tested.

Type:

Zirconium titanate type: Zirconium titanate is used as the sensitive material, with high sensitivity and selectivity.

Zirconium oxide type: Similar to the oxygen sensor, but the sensitive layer material is different, mainly used to detect NOx.

Position: Usually installed before the SCR system to monitor the NOx concentration entering the SCR system.