Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Oxygen sensor heater control
circuit... / Circuit description
Toyota Corolla (E120): Circuit description
Refer to dtc p0130
Hint
: the ecm provides a pulse width modulated control circuit to adjust current through the heater. The heated oxygen sensor heater circuit uses a relay on the b+ side of the circuit.
Monitor description
The ecm uses the heated oxygen sensor information to regulate the air–fuel ratio close to a stoichiometric ratio. This maximizes the catalytic converter’s ability to purify the exhaust gas. The sensor detects oxygen levels in the exhaust gas and sends this signal to the ecm.
The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of the platinum coated zirconia and includes an integrated heating element. The heated oxygen sensor has the characteristic whereby its output voltage change suddenly in the vicinity of the stoichiometric air–fuel ratio. When heated, the sensor becomes very efficient. If the temperature of the exhaust is low, the sensor will not generate useful voltage signals without supplemental heating. The ecm regulates the supplemental heating using a duty–cycle approach to regulate the average current in the heater element. If the heater current is out of the normal range, the sensor’s output signals will be inaccurate and the ecm cannot regulate the air–fuel ratio properly. When the heater current is out of the normal operating range, the ecm interprets this as a malfunction and sets a dtc.
Example: the ecm will set a high current dtc if the current in the sensor is more than 2 a when the heater is off.
Similarly, the ecm will set a low current dtc if the current is less than 0.25 A when the heater is on.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Component operating range
Monitor result (mode 06 data)
Refer to page 05–27 for detailed information on checking monitor status.
Wiring diagram
Refer to dtc p0130
Other materials:
Diagnostic trouble code chart
The inspection procedures are shown in the table below. This table allows
efficient and accurate troubleshooting
using the diagnostic trouble codes displayed in the diagnostic trouble code
chart. Proceed with
troubleshooting in accordance with the inspection procedures listed in the
diagnost ...
Radio broadcast cannot be received (bad reception)
Inspection procedure
1 Check if radio auto–search functions properly
Check if the radio auto–search functions properly.
Perform the auto–search of the radio and check that it functions
normally.
Standard: the radio auto–search functions properly.
2 Check optional ...
Registering and connecting from the “Bluetooth* Setup” screen
To display the screen shown below, press the “SETUP” button and select “Bluetooth*”
on the “Setup” screen.
1 Select to connect the device to be used with multimedia system.
2 Select to register a Bluetooth® device to be used with multimedia system.
3 Select to set detailed Bluet ...