Honda EP3 Service Manual page 253

Fuel and Emissions Systems
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System Descriptions (cont'dl
Secondary Heated Oxygen Sensor (Secondary HO2S)
The secondary HO2S detects the oxygen content in the
exhaust gas downstream of the three way catalytic
converter (TWC) and sends signals to the ECM which
checks the efficiency of the TWC. To stabilize its output,
the sensor has an internal heater. The secondarv HO2S
i s i n s t a l l e d i n t h e T W C .
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ELEMENT
SENSOR
TERMINALS
HEATER
TERMINALS
Starting Control
When the engine is started, the ECM provides a rich
mixture by increasing injector duration.
Throttle Position ITP) Sensor
The TP sensor is a potentiometer connected to the
throttle valve shaft. As the throttle position changes, the
sensor varies the signal voltage to the ECM. The TP
sensor is not replaceable apart from the throftle body.
ELEMENT BRUSH HOLDER
gRUSH
11-28
Vehicle Speed Sensor (VSS)
The VSS is driven by the differential. lt generates a
pulsed signal from an input of 5 volts. The number of
pulses per minute increases/decreases with the speed
of the vehicle.
BEARING