故障现象一辆2007款雷克萨斯RX400H车,装备型号为3MZ-FE发动机和P310自动变速器,行驶里程约为40万km,因经常缺少冷却液而进店检修。故障诊断接车后对车辆进行检查,首先观察仪表,发动机温度正常,无故障灯点亮;检查发动机运转情况,发动机运转平稳;用故障检测仪读取故障代码,无故障代码存储。经询问驾驶人得知,该车一直使用无水防冻液作为发动机冷却介质,前段时间突然出现发动机温度过高的 Symptom A 2007 Lexus RX400H vehicle, equipped with a 3MZ-FE engine and a P310 automatic transmission, has a mileage of about 400,000 km and is often overhauled due to lack of coolant. Fault diagnosis After the car to check the vehicle, first of all observe the instrument, the engine temperature is normal, no fault light lit; check the engine operation, the engine running smoothly; fault detector read the fault code, fault-free code storage. After asking the driver that the car has been using anhydrous antifreeze as the engine cooling medium, suddenly appeared some time ago the engine temperature is too high