the ECM. When the intake air volume is low (the exhaust gas temperature is low), current flows to the heater to heat the sensor, in order to facilitate
accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by
the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.
A three-way catalytic converter is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less
harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the
stoichiometric air fuel ratio.
*: Value changes inside the ECM. Since the air fuel ratio sensor uses the current output element, the current is converted to a voltage inside the
ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.
HINT
- DTCs P2195 and P2196 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
- DTCs P2197 and P2198 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that does not include cylinder No. 1.
- When any of these DTCs are set, check the air fuel ratio sensor output voltage by entering the following menus: Powertrain /
Engine / Data List / A/F Control System / AFS Voltage B1S1 or AFS Voltage B2S1.
- Short-term fuel trim values can also be read using the Techstream.
- The ECM regulates the voltages at the A1A+, A2A+, A1A- and A2A- terminals of the ECM to a constant level. Therefore, the
air fuel ratio sensor output voltage cannot be confirmed without using the Techstream.
- If an air fuel ratio sensor malfunction is detected, the ECM sets a DTC.
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