Where is the engine speed sensor located?
3 Answers
Engine speed sensors are typically located inside the distributor, mounted on the clutch housing of the transmission, at the front or rear end of the crankshaft. Pulse signal-type speed sensors are used to measure engine speed. Some sensors may also be installed at the front end of the crankshaft, the front end of the camshaft, or on the flywheel. The specific installation location depends on the type of engine speed sensor. The engine speed sensor, also known as the crankshaft position sensor, is one of the critical sensors in the electronic fuel injection engine control system. Its function is to detect the engine speed, determine the position of the crankshaft, detect signals for the piston's top dead center and crankshaft rotation angle, and transmit these signals to the ECU to control ignition timing and fuel injection timing.
When I was repairing my car, I noticed that the position of the engine speed sensor is actually quite fixed. In most models, it is installed near the crankshaft pulley or flywheel because it needs to monitor the crankshaft rotation speed in real time. If you open the hood, you'll find it in a small hole at the front or rear of the engine. For example, Toyota models often place it near the crankshaft pulley, while Ford vehicles may position it closer to the flywheel side. I once encountered an engine shaking issue caused by the sensor being covered in dust, which was resolved by cleaning it with a cloth. I recommend checking its plug for looseness during routine inspections—this small component may seem insignificant, but if it fails, it can affect ignition timing, causing minor issues like jerky driving or even stalling. Different engine layouts can lead to slight variations in its position, and in older models, it's often more visible under the chassis.
When DIY car repairs, I often need to locate the RPM sensor, which is usually hidden deep in the engine, with its position varying by vehicle model. On most standard cars, if you look under or to the side of the engine, you'll find it attached to the crankcase or flywheel housing, with a wire connected to the ECU nearby. From my experience with Honda, it's located near the oil pan; for Mercedes, it's above the exhaust pipe. Remember to disconnect the power before working, use a wrench to remove the protective cover, avoid oil contamination, and test if the signal is restored after a simple cleaning. Though small, this little component controls the accuracy of the tachometer, and checking it yourself can save you towing fees.
