We have an customer send a vedio to us, everything in the vedio is fine, and the machine looks working very well. But he said that when he remove the vibration sensor from machine, the machine start to beep, but checking on the top side control panel, all the lights are correct, no any one alarming light is on. Then we think it is caused by not connect the correct pipe, because when remove vibration sensor, machine can only work by feel enough suction, if the suction is not good, it will beep. But the customer told me that they are very experienced at car, it is impossible for them to connect wrong pipe. And we told customer that vibration sensor is only back up accessory, can not use it normally, when need to use it for some testing, we will told customer, otherwise just keep it away is fine. And we ask him to answer three question from us. Firstly, ask him check and cfm if the adjust valve and metal nozzle at end is fully open. Secondly, ask him check if he can see any cleaner agent flow in the long transparent pipe and come into car engine. Thirdly, we ask him to make the negtive pressure sensor a circuit, no need connect machine with car, and check at this moment, after remove the vibration sensor, the machine will also beep or not? If now the beep stopped, that means he really connect wrong pipe without suction.