Toyota 2GR-FE Manual page 544

ES–388
DTC
DTC
DESCRIPTION
HINT:
• DTC P2A00 indicates malfunctions related to the bank 1 A/F sensor.
• DTC P2A03 indicates malfunctions related to the bank 2 A/F sensor.
• Bank 1 refers to the bank that includes cylinder No. 1.
• Bank 2 refers to the bank that includes cylinder No. 2.
• Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and
ES
located near the engine assembly.
• Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
• Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and
located near the engine assembly.
The A/F sensor generates voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is
used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the
deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor
malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F sensor is the planar type and is integrated with the heater, which heats the solid electrolyte
(zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust
gas temperature is low), a current flows into 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 (TWC) is used in order to convert the carbon monoxide (CO), hydrocarbon
(HC), and nitrogen oxide (NOx) into less harmful substances. To allow the TWC 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 A/F sensor is the current output element, a current is
converted to a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors
will show a constant voltage.
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
A/F Sensor Circuit Slow Response (Bank 1
P2A00
Sensor 1)
A/F Sensor Circuit Slow Response (Bank 2
P2A03
Sensor 1)