Complete list of common system faults and troubleshooting methods for SCR part3
1.Fault phenomenon: The SCR system fails to execute the startup program, the reducing agent pump will stop working, and the system cannot establish pressure.
Fault diagnosis and troubleshooting methods: Focus on checking and starting program related parts, such as exhaust temperature sensor, nitrogen oxide sensor, reducing agent tank temperature sensor, reducing agent tank level sensor, reducing agent pump, heating relay, heating solenoid valve, ambient temperature sensor, etc. When the vehicle is in a low-temperature environment, first check the reducing agent heating system to ensure that the heating function is normal, and promptly eliminate any faults in the wiring harness between electronic components. The main reasons for low reducing agent pressure are leakage at pipeline joints, blockage of primary and main filters, and abnormal pressure sensors. Therefore, the component can be replaced.
2.Fault phenomenon: The nozzle is blocked and there is a phenomenon of rising spray.
Fault diagnosis and troubleshooting methods: Fuel injector failure. If the actual fuel injection amount of the injector is less than the set fuel injection amount, it will result in a relatively large injection amount of reducing agent. Exhaust temperature is one of the conditions for adjusting the injection amount of reducing agent. If the deviation of the reducing agent pressure value is too large, it will cause the correction of the reducing agent injection amount to be too large, which in turn will lead to excessive reducing agent injection. If the reducing agent nozzle gets stuck in the normally open position, it will cause the amount of reducing agent sprayed to significantly exceed the set value, resulting in excessive spraying of reducing agent. There is an ammonia smell in the exhaust gas caused by excessive injection of reducing agent. The reason is that too much ammonia is generated by the decomposition of urea in the reducing agent, which is not used and is discharged from the tailpipe. Focus on checking whether there is a malfunction in the urea solution heating system, and generally prohibit substandard or inferior urea solution during maintenance.
Bosch airless SCR system