Air Fuel Ratio (A/F) Sensor, Heated Oxygen Sensor (Ho2S) Heater Control Outline [13B-Msp]; Air Fuel Ratio (A/F) Sensor, Heated Oxygen Sensor (Ho2S) Heater Control Block Diagram [13B-Msp] - Mazda RX-8 2009 Service Highlights

Cleaning mode
If any of the following conditions are met, this mode is executed to remove foreign material in the OCV oil
passages:
— Engine start mode is completed.
— The oil pressure input from the oil pressure sensor remains at a certain value or more after a specified time
has elapsed since the engine was started.
Operation
The OCV alternately controls the target current between low and high levels at certain intervals. After
repeating this operation several times, foreign material that has penetrated the OCV is removed and the
cleaning mode is completed.
— The oil pressure input from the oil pressure sensor remains at a certain value or less after a specified time
has elapsed since the engine was started.
Operation
Because there may be an oil leakage concern from the pipes, the passage between the OCV and
metering oil pump is closed so that oil-feed into the metering oil pump stops.
Periodic cleaning mode
This mode performs at specified time intervals to remove foreign material in the OCV oil passages. (except
during high engine speed, high engine load)
Operation
The OCV controls the target current on the lower side for a specified period of time. After executing this
operation one time, foreign material penetrating the OCV is removed and the periodic cleaning mode is
completed.
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AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OUTLINE [13B-
MSP]
Stabilized oxygen concentrations, even when the exhaust gas temperature is low, are detected by controlling of
the A/F sensor and HO2S, enabling feedback control of the fuel injection control even during cold-engine
starting, improving emission performance when cold.
When the exhaust gas temperature is high, the A/F sensor and HO2S is protected from sharp rises in its
temperature by stopping energization to the A/F sensor heater and HO2S heater.
Emission performance improvement and protection of the A/F sensor and HO2S have both been achieved by
the duty control of the A/F sensor and HO2S according to the engine operation conditions (exhaust gas
temperature).
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AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL BLOCK DIAGRAM
[13B-MSP]
The PCM determines the engine conditions based on input signals and sends an operation signal to the A/F
sensor or HO2S.
ECT SENSOR
A/F SENSOR
HO2S
BATTERY
ECCENTRIC SHAFT
POSITION SENSOR
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01-40–22
CONTROL SYSTEM [13B-MSP]
PCM
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id0140g1782100
A/F SENSOR HEATER
HO2S HEATER
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