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A tiny sensor keeps everything from the two-cylinder Fiat to the 887-horsepower Porsche supercar.

We tend to view limited-production supercars (such as the hybrid Porsche 918 Spyder) as exclusive vehicles made of customized top-notch parts. This may not always be the case. Although you won't find the 918's 4.6-liter naturally aspirated V-8 in any other road car, this powerful engine shares a key part with a host of walking machines including the Fiat Panda.

Welcome to the parts department, where we track basic car parts to their strangest destinations.

Automotive industry supplier Bosch produces a variety of engine knock sensors, including part numbers. 0-261-231-173. Like other knock sensors in the Bosch series, this sensor is bolted to the engine block to detect abnormal vibrations, which can indicate that the engine is experiencing knocking or "knock". When knocking is detected, the engine computer will adjust the refueling or timing to prevent catastrophic engine damage. It is part of the safety blanket of engine programming to ensure that everything is running properly. The programming is specific to each application, but the knock sensor itself can be installed on various engines.

The sensor itself is small and compact, with its head protruding less than 3/4 inch. It is bolted to the engine block and weighs only 1.7 ounces. This tiny size allows it to be installed in a variety of applications, from the third-generation (2011-present) Fiat Panda's 875 cc, 84-horsepower turbocharged two-cylinder engine to the 918 Spyder's V-8. The robustness of this small sensor also allows it to work in a variety of applications: the sensor can detect vibrations up to 800 m/s2 while operating at temperatures as low as -40 degrees Fahrenheit or as high as 302 degrees Fahrenheit. It also has an IPX9K rating, which is currently the highest level of waterproof ingress protection.

The knock sensor itself is contained in a circular housing; the protrusion is where the wire harness is inserted.

According to the current parts catalog, the earliest variants of this sensor appeared in the 986-generation Porsche Boxster and the 996-generation Porsche 911 in the late nineties. It then appeared on the 79-horsepower 1.2-liter four-cylinder engine of the second-generation Fiat Punto in 1999. From there, it expanded to most of Fiat's product line, including the low-profile two-cylinder Panda, and in the early 2000s entered cars including the Lancia Thesis and Opel Corsa.

In addition to low-power economy cars like Panda and Opel Corsa and Agila, this component is also found in some interesting cars, such as the Opel Tigra TwinTop. The knock sensor first tasted powerful power in 2006 when it was installed on the 514-horsepower 4.5-liter twin-turbocharged V-8 engine of the Porsche Cayenne Turbo S. The Porsche 911 Turbo and 911 GT2 finally reached their most powerful destination, the 600-horsepower heart of the 918 Spyder.

Although the 918 is indeed an exciting vehicle, it is not the most interesting thing our small knock sensor has. Bosch has repackaged the components for racing, which are available under the part number. KS4-P in the Bosch racing catalog. This leads us to a variety of competition applications, from drifting cars running independent ECUs in their home-made engine switches to professionally driven GT3 racing cars.

Like many other products in the automotive industry, this sensor has leapt to crossovers and SUVs, appearing in Jeep Renegade and Fiat 500X. Fiat Connect also found this small sensor nestled in the engine compartment of the Alfa Romeo 4C, although it has never been far from the roots of the Porsche: for now, you will find this exact same sensor and crocodile in the engine compartment of the 718 Boxster.

The sealed plastic knock sensor may look like an ordinary piece of equipment, but next time you pry one off a Fiat engine at the junkyard, remember that it helps power Porsche’s most legendary supercar .