Information source: a fixed AL4 was complained of oil leak and return to factory washing and haven't found oil spill after testing.

Emergency measures: we sent our technical staff to the site, we found the main oil pressure is too high after checking data by computer. It keep at 10.8kg/m², normal is 2.7kg/m². So we can judge solenoid valve doesn't work or jammed, we should change EPC solenoid valve, then fault is solved.

Analysis of causes: It was found that the regulated function of replaced EPC was invalid. After dissection, we found it was jammed at plastic seat, and it can't move smoothly. After careful checking, we found the reason is that it is not polluted by impurity or attrition, because the material of solenoid valve has Oil resistant composition, so it become out of shape by external force(for example drop, crash) or high temperature. But look from the appearance of solenoid valve, we haven't found external force, so we judge it was affected by high temperature. From the whole process, when we test bench, the highest temperature is about 90°C, it can't make solenoid valve be out of shape. At the same time, our client found the problem when he assembled the car(the situation that it has Abnormal high temperature while driving doesn't exist.) the most possible situation is it star the test of EPC by computer under condition the electrical machine is not started. It lead coil produce high temperature and cause transformation when it under no condition of Lubrication and cooling.