Secondary Heated Oxygen Sensor (Secondary H02S1); Starting Control; Throttle Position; Vehicle Speed Sensor - Honda Civic 2002-2003 Service Manual

Fuel and Emissions Systems
System Descriptions (cont'd)
Secondary Heated Oxygen Sensor (Secondary H02S1
The secondary H02S 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 secondary H02S
is installed in the TWC.
ZIRCONIA
ELEMENT
HEATER
Starting Control
SENSOR
TERMINALS
HEATER
TERMINALS
When the engine is started, the ECM provides a rich
mixture by increasing injector duration.
Throttle Position (TPI 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 throttle body.
ELEMENT BRUSH HOLOER
TERMINAL
BRUSH
11-28
Vehicle Speed Sensor (VSSI
The VSS is driven by the differential. It generates a
pulsed signal from an input of 5 volts. The number of
pulses per minute increases/decreases with the speed
of the vehicle.
TERMINALS
CIRCUIT
BOARD
BEARING
GEAR
SHAFT