Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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4) Malfunction Mode
z Short-circuit or open-circuit of sensor;
z Distorted, error, and suspicious signal;
z Unstable sensor signal;
z Sensor signal is out of range.
5) Troubleshooting
Use diagnosis instrument to check the trouble code and determine the malfunction position. Mainly check whether the
sensor is installed in place and whether the clearance is normal, check the sensor circuit whether there is short-circuit
or open-circuit to grounding wire, check whether there is short-circuit or open-circuit to the power supply, and check
whether the circuit is consistent with the given pin definition.
3. Pressure difference sensor
1) Overview
z The pressure difference sensor is functioned to real-time monitor the pressure drop of the POC and determine
whether the after-treatment system is working normally. The pressure at two ends of the POC is introduced via
two pressure ports of the sensor and then the sensor converts the measurement into voltage value and feeds back
to control unit. This can not only guarantee the sufficient oxidization of grains, but also prevent the blockage of
catalytic converter.
z The pressure difference sensor and the POC are connected via stainless steel pipe and high temperature rubber
hose. The pressure is introduced via stainless steel pipe, which is at least 250mm in length, from two sides of
POC and then is led to the pressure difference sensor via high temperature rubber hose, which is capable of
enduring more than 150ºC.
2) Working Principle
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