A Honda accord car with a mileage of about 100 thousand km and a F22B1 engine. User response: after the car starts the engine, the dashboard engine fault light (CHECKENGINE lamp) has been lit. After receiving the car, the 2 needle diagnosis seat is found in the rear of the sundries box, two terminals are connected, the ignition switch is opened, the engine fault lights flicker and the reading fault code is 22, which means that the variable throttle pressure switch line is bad. The vehicle adopts the variable valve timing and electronic control hydraulic tappet mechanism, known as the VTEC control system. The engine control module is controlled by the engine speed signal, the speed signal coolant temperature sensor signal and the engine load signal, according to the principle of the VTEC control system. When the engine speed is above 2500r/min, the speed reaches more than 5km/h, and the temperature of the coolant reaches more than 5.3 C, the main and the auxiliary inlet valve of the VTEC control system will be opened synchronously to improve the efficiency of the intake. When the engine idling, the middle rocker will open a smaller opening of the main and vice intake valves in a smaller range. When the engine speed is above 4800r/min and the coolant temperature reaches above 60 C, the main and secondary intake valves are opened to increase intake efficiency. The variable throttle pressure switch is located under the variable valve solenoid valve (VTEC solenoid valve), and the engine control module monitors the variable valve solenoid valve according to the variable throttle pressure switch signal. The resistance of measuring VTEC solenoid valve is 22 ohms, which is within the standard value range. Check the variable valve pressure line, 12V reference voltage line and ground wire are good, remove variable valve pressure switch, found dirty. The measured resistance value after cleaning is 0 ohms, indicating that the components themselves are good. Check the oil, the oil is dirty and black. Replace the oil and oil filter, install the variable valve pressure switch, remove the fuse from the engine system, and erase the trouble code. Test the car, the fault is completely eliminated. When the engine speed is low, the main intake valve operates normally, and the secondary intake valve only moves with tiny opening to prevent fuel accumulation at the intake port. The difference between the main and vice intake valve opening is to make the mixture into the cylinder to generate eddy current, so as to achieve the goal of reducing fuel consumption. When the engine runs at high speed, the timing valve piston is pushed by the oil pressure. The timing valve piston pushes the two synchronous pistons to move together, making the 3 rocker arms joined together and driven by the central cam, thus making the main and secondary inlet valve greater opening and increasing the engine power. When the variable valve oil pressure solenoid valve function, the variable valve pressure switch should be disconnected. If the variable valve solenoid valve is not open (the oil pressure does not work), the variable valve pressure switch is 0 Omega. The failure reason of this case is the oil scale adhesion variable valve pressure switch, which is still in the disconnected state after closing. The engine control module determines the variable valve pressure switch to work badly, so the fault code is set to 22.