Engine Electrical System

value, failure mark restores.
Installation hint: tightening torque is 20±5Nm.
Pins:
1 Knock sensor signal 1 (ECU19#)
2 Knock sensor signal 2 (ECU20#)
Troubleshooting: mainly check if there is short circuit
or open circuit on the connection between 2 lines on
sensor and corresponding ECU pins.
If gasket is added during installation; if tightening
torque is proper.
If there is stitching defect between sensor and cylinder,
or there is foreign matter between them.
※Oxygen Sensor
Purpose: this sensor is designed to provide the
information that if there is surplus oxygen after full
combustion of fuel, which is injected into engine
cylinder in the intake air. ECU, when applying this
information, can carry out fuel quantitative
closed-loop control so as to achieve utmost conversion
and purification of the three major toxic elements (HC,
CO and NOX) in the engine exhaust with the
application of three-way catalytic converter.
Composition and principle: the sensing element of
oxygen sensor is a porous ceramic pipe, the outer side
of pipe wall is surrounded by engine exhaust, while
inner side vents to atmosphere. According to inside
and outside oxygen concentration difference, sensor
figures out indirectly fuel injection pulse width, and
then transfers the information to ECU, and the ECU
controls the injection again.
The working voltage of oxygen sensor fluctuates
between 0.1-0.9V, 5-8 variations in 10 seconds is
required; if lower than such frequency value, it shows
that the sensor is aged, and needs replacement. The
said sensor is unrepairable.
Failure diagnosis: ECU monitors on various sensors,
actuators, power amplification circuits and sensing
circuits. In case any of the following situations occurs,
failure mark of the oxygen sensor is set.
Accumulator voltage is unreliable
Oxygen Sensor
Circuit diagram
of
Oxygen sensor
E-11
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