2016 – MX-5 – Engine

HEATED OXYGEN SENSOR (HO2S) [SKYACTIV-G 2.0]

Purpose

• Detects the oxygen concentration (air/fuel ratio) in the exhaust gas as basic information for mainly determining the fuel injection amount and as information for determining the deterioration of the catalytic converter.

Function

• Detects the oxygen concentration (air/fuel ratio) in the exhaust gas and sends it to the PCM as an oxygen concentration (air/fuel ratio) signal.

  HO2S characteristic

  

• The HO2S detects rich/lean of the oxygen concentration compared to the theoretical air/fuel ratio.

Construction

• The HO2S is located on the pipe between the warm-up three-way catalyst (WU-TWC) and the three-way catalyst (TWC) of the catalytic converter.

  

• A zirconia element has been adopted for the detection area of the HO2S.

• A zirconia element generates voltage according to the difference in the oxygen concentration between atmosphere side and exhaust gas side.

  

• The zirconia element is kept at a specified temperature by the heater for quick activation.

Operation

• Sends signals, which vary according to the oxygen concentration (air/fuel ratio), to the PCM.

• When the oxygen concentration in the exhaust gas is high, the output voltage is low because there are almost no difference in the oxygen concentration. (Output voltage approx. 0—0.5 V)

• When the oxygen concentration in the exhaust gas is low, the output voltage is high because the difference in the oxygen concentration is large. (Output voltage approx. 0.5—1.0 V)

• The PCM applies approx. 1.5 V to the voltage output from the HO2S to prevent false diagnosis of the HO2S output voltage.

  

Fail-safe

< Previous Next >