A 2020 GLE 350e 4MATIC smart edition Mercedes-Benz GLE PHEV model, users reflect that the vehicle is driving, the engine failure lights are on, the engine water temperature is high and low, so come to the shop to repair the cause of the vehicle failure.
The car is a plug-in hybrid model, fuel-powered system with a 2.0T turbocharged engine, an engine model of 274 920, a maximum power of 155 kW, a peak torque of 350 N·m, and a 9-speed automatic transmission for the transmission system.
In terms of electric system, the battery type equipped with the car is a lithium-ion battery, the battery capacity is 31.2kWh, the total power of the motor is 100kW, the total torque of the motor is 435N·m, the system comprehensive power is 245kW, and the system comprehensive torque is 785N·m.
After receiving the vehicle, it is found that the engine fault light of the instrument is lit, and the vehicle-related control unit is read by the diagnostic computer, and the engine control unit is found to have the following fault code stored
P012800 The coolant temperature is lower than the coolant thermostat standard
According to the fault code stored on the engine computer, check the workshop manual, and the possible causes of failure are as follows
1. Coolant thermostat heater element
2. Engine water pump failure
3. The circuit of the coolant thermostat heating element is open or short-circuited
First of all, the engine of the car adopts a thermal energy management system, the car engine water pump is designed with a ball valve, the water pump ball valve is controlled by the vacuum control valve of the engine, when the engine starts cold, the engine detects that the water temperature is low, and the ball valve is controlled to be closed, so that the antifreeze inside the engine is circulated. So that the water temperature of the engine reaches the optimal operating temperature as soon as possible.
The engine pump was tested with a manual vacuum pump, and it was found that the ball valve inside the pump was active normally, and the opening degree was larger with the larger the vacuum degree, indicating that the internal activity of the pump was normal and there was no jamming phenomenon.
So the vehicle's electronic thermostat is checked, with the diagnostic computer to read the actual value of the engine control unit thermostat, found that the heating load rate of the thermostat is 0%, and the engine water temperature is not up to 97.5 ° C, when the water temperature reaches 97 ° C, it falls to 90 ° C, indicating that the thermostat has been in an open state, otherwise the engine water temperature will not rise to more than 100 ° C, and the engine engine water temperature 105 ° C Fan began to operate. Therefore, the maximum water temperature of 97.5 °C is obviously not normal.
Therefore, the electronic thermostat of the vehicle engine is disassembled and inspected, and it is necessary to disassemble the intercooler and the intake manifold to remove the electronic thermostat, which is relatively troublesome.
When the electronic thermostat is removed, in order to determine whether the electronic thermostat is damaged, the plug of the electronic thermostat is measured with a multimeter to measure the resistance, and the heating resistance of the electronic thermostat of the car is infinite, and the electronic thermostat heater resistance of the normal vehicle should be within the normal range of 8.5-10.5Ω at an ambient temperature of 25 ° C, and with the change of ambient temperature, the resistance will also change to a certain extent, but the change is not large.
After replacing the new electronic thermostat, also replaced with a new antifreeze, after installation, eliminate the fault code, many times the test drive is normal, there is no reproduction of the fault code, and the engine water temperature can also reach about 100 ° C.
In fact, in addition to the P0128 fault code of the engine of this model, there is also a fault code of the P0597 thermostat heater, which can be eliminated after replacing the thermostat, and there is also a need to replace the engine water pump. Therefore, there are also peer pumps and thermostats to replace together to solve the problem, so you need to check to know what is the cause of the failure.