1, SCR system mainly includes: urea aqueous solution tank, delivery device, metering device, injection device, catalytic converter and temperature and exhaust sensors.
2, urea nozzle as the role of the injection device is in accordance with the instructions of the controller to carry out the injection of urea solution. Due to the influence of various factors, the urea nozzle is prone to clogging, crystallization and so on.
3, urea nozzles once the crystallization of blocked nozzles will lead to a complete loss of spray effect, the ECU computer control system will be recognized after the alarm, the engine limit torque or cause damage to the air pump.
4, the injection system parts if clogged, need to replace the relevant assembly parts, and the market price of the general SCR urea nozzle ranging from 2000-3000. The cost of replacing SCR system parts will aggravate the cost of vehicle owners.
Troubleshooting:
1, check the nozzle connector, there is no damage or short-circuit;
2, measure the K10 pin voltage, about 24V, out of the normal range;
3, check the whole vehicle harness big plug, found that the nozzle K10 wiring harness and the other charged wiring harness short-circuit
4, repair the wiring harness, the fault eliminated.
Conclusion: The nozzle harness (K10) in the large plug of the vehicle harness is shorted to the power supply.