A Bosch Switching-Type Oxygen (O2) sensor uses a zirconia Nernst cell ceramic element to measure the oxygen content in exhaust gases. As the air-fuel mixture shifts between rich and lean, the sensor rapidly switches its voltage output. These fast transitions provide the ECU with real-time lambda data, allowing precise fuel adjustments for stable combustion, effective catalytic converter operation, and reduced emissions.

Modern EPA and Euro 6 emissions standards demand accurate air-fuel-ratio control to ensure clean and efficient combustion. Oxygen (O2) sensors supply the ECU with continuous lambda information, enabling proper catalytic converter function, reduced fuel consumption, and minimized harmful emissions across all operating conditions.

A Bosch Wideband A/F Oxygen (O2) sensor uses a planar pump-cell design to measure the air-fuel ratio continuously across the full lambda range. Instead of switching between rich and lean, the sensor regulates internal pump-cell current to maintain a precise oxygen balance within the sensing chamber. This current is interpreted by the ECU as exact air-fuel-ratio information, allowing highly accurate mixture control for stable combustion, improved efficiency, and reduced emissions.

An Oxygen (O2) sensor should be replaced if a check-engine light appears and diagnostic trouble codes related to fuel-trim or sensor performance are stored, or if symptoms such as poor fuel economy, failed emissions tests, rough idle, or sluggish acceleration occur. Sensors contaminated by oil, coolant, fuel additives, or physical damage should also be replaced to restore accurate air-fuel-ratio control.