Primary Heated Oxygen Sensor; Secondary Heated Oxygen Sensor; Throttle Position (Tp) Sensor; Vehicle Speed Sensor (Vss) (M/T) - Honda 2002 Accord Manual

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Table of Contents

Fuel and Emissions Systems

System Descriptions (cont'd)

Primary Heated Oxygen sensor (Primary H 0 2 S )

The p r i m a r y H 0 2 S detects the o x y g e n content in the

exhaust gas and sends signals t o the ECM/PCM w h i c h

varies the duration of fuel injection accordingly. To

stabilize its o u t p u t the sensor has an internal heater.

The p r i m a r y H 0 2 S is installed in the exhaust m a n i f o l d .

By c o n t r o l l i n g the air fuel ratio w i t h primary H 0 2 S and

secondary H 0 2 S , the deterioration of the p r i m a r y H 0 2 S

can be evaluated by its feedback period. W h e n the

feedback period exceeds a certain value d u r i n g stable

d r i v i n g conditions, the sensor is considered

deteriorated and the ECM/PCM sets a DTC.

Z I R C O N I A

T E R M I N A L S

Secondary Heated Oxygen sensor (Secondary H 0 2 S )

The secondary H02S detects the oxygen content in the

exhaust gas downstream of the Three W a y Catalytic

Converter ( T W O and sends signals to the ECM/PCM

w h i c h varies the duration of fuel injection accordingly.

To stabilize its output, the sensor has an internal heater.

The secondary H02S is installed in the TWC.

Throttle Position (TP) 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/PCM. The

TP sensor is not replaceable apart f r o m the throttle

B R U S H H O L D E R

R E S I S T O R

T E R M I N A L

Vehicle Speed Sensor (VSS) (M/T)

The speed sensor is driven by the differential. It

generates a pulsed signal f r o m an input of 5 volts. The

number of pulses per minute increases/decreases w i t h

the speed of the vehicle.

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T E R M I N A L S

Troubleshooting