NOx Sensors for Engine Exhaust Gas


NOx Sensors for Engine Exhaust Gas Compatible with both 12V and 24V voltage systems
NOx Sensors for Engine Exhaust Gas Compatible with both 12V and 24V voltage systems

Using zirconia (ZrO2) thick film technology, NGK has developed NOx sensors capable of measuring NOx density in motor vehicle exhaust gas. Attached directly to vehicle exhaust pipes, these NOx sensors allow precise measurements of NOx concentration in exhaust gas for extended periods.

NGK is bringing these NOx sensors to market which integrated with sensor control units capable of operating independently of engine control units (ECUs).


  • As zirconia sensors, the products can be inserted directly into high-temperature exhaust gas.
  • Direct insertion results in high response and steady output for extended periods.
  • Integrated digital circuit allows direct connection to ECUs.
  • Digital communication feature is ideal for use with on-board exhaust gas diagnostic (OBD) systems.

Primary uses

Potential applications of NOx sensors as an NOx emissions reduction technology
for meeting increasingly strict exhaust gas regulations:

  • Monitoring NOx concentration downstream of NOx adsorber catalysts to control NOx adsorber catalyst regeneration
  • Monitoring NOx concentration before and after selective catalytic reduction (SCR) to control and optimize urea injection
  • NOx-OBD: Self-diagnostics by sensor and unit to identify wear in catalysts and other components

Sample measurements

Sample measurements

In measurements of diesel engine exhaust gas, these sensors exhibit linear properties closely matching those of chemical luminescence detector (CLD) NOx analyzers.

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