For the normal car owner, there’s often some misperception about car sensors and what they actually do. To explain, let’s go back in time a bit. At some point the majority of drivers, whether they’re young or old, will experience difficulty in parking flawlessly. It could be due to the way someone else has parked or being rushed by traffic as you struggle to Parallel Park. Whatever the excuse we come up with, we probably end up thinking to ourselves, “I wish I had some parking sensors”. Once the territory of high end, expensive, cars.


Remember, there are three things essential for the internal combustion engine to work: air, fuel, and spark. Engine controller systems manage all of those, as well as spark timing and other factors. A generation ago, these functions were organized with mechanical or electromechanical systems. The carburetor would regulate fuel metering and mixture, as well as cold idle speed. A motorized distributor would manage spark delivery and would rely on vacuum to advance or retard timing according to engine load, and a mechanical fuel pump (driven off of the camshaft) would send fuel from the fuel tank to the carburetor.

These engine control systems were good-looking maintenance-intensive—in those days, an engine would need a detailed tune-up every 35,000 miles or so to keep running right. By the late ’70s, spark delivery was coped up with an electronic module rather than mechanical breaker points, and by the ’80s emissions concerns forced other changes in engine management. Initial engine management systems were transitional technology with sensors delivering information to an analog processor, which would then give conclusions on engine functions. The problem with these early setups was that the analog processor was programmed with predetermined limits and could not respond energetically as an engine started to wear and become “looser.”

By the ’90s, carburetors had been exchanged with fuel injection, and the distributor/ignition coil/plug wires on many engines had been replaced with a high-voltage coil-on-plug setup. For all these systems to work properly, though, they need information on what’s up-to-the-minute with emissions, engine load, air volume, and other factors. That’s where sensors come into play.


The O2 sensor, for instance, transmits information on the content of exhaust gases, which the engine processor uses to readjust fuel metering and emissions. The MAP and MAF sensors observe the amount of air entering the engine, and the crank and cam position sensors impact ignition timing and fuel delivery. Sensors such as the throttle position sensor and vehicle speed sensor read engine load and help determine transmission shift points and fuel metering.


All these sensors send a signal back to the engine computer, and this signal should stay within a definite voltage range. If the voltage from the sensor falls outside of these limitations, it will register a “trouble code” in the computer and lighten the check engine light (CEL). In some instances, it may take multiple events from the sensor in order to store a trouble code and light up the CEL; once the CEL is well-lit, however, a tech can hook up a code reader to the car’s diagnostic port and quickly get access to the trouble codes, which are a starting point for diagnostics. From there, it’s a concern of interpreting the code and deducing what failed for the sensor to send these readings. These are a starting point for diagnostics.

Parking Sensors – What Are They? Parking sensors are great tiny devices that are frequently installed into a vehicles rear bumper and activated when the vehicle is shifted into reverse. Their main purpose is to alert you to anything that is behind a vehicle whilst it is reversing.

Why Should You Have Parking Sensors?

Lots of modern day cars have large blind spots that can make parking and turning problematic. Parking sensors are great at serving you reverse into tight parking spaces, as well as notifying you to anything that may be behind your vehicle such as high pavements, bollards, other vehicles and small children. Though they may be slightly exasperating, due to their high pitched shrill, they are great at averting avoidable knocks to a vehicle.

How Do Parking Sensors Work?

There are three main kinds of rear parking sensors:
1-Ultrasonic Sensors
2-Rear Facing Cameras
3-Electromagnetic Sensors

Ultrasonic Sensors are the most common type of parking sensor and are usually implanted within the rear bumper of a vehicle. You’ve probably noticed lots more vehicles sporting these small circular devices (usually 4 or 6 across the bumper) that tend to be the same colour as the bumper of the vehicle. This type of sensor works on the same standard as naval sonar devices. By emitting high frequency sound waves and measuring how long it takes to come back to the sensor it can inform you of how close you’re getting to an obstacle.

Rear Facing Cameras work by giving you a live feed to the infotainment screen on the car once you shift gears into reverse. You can also get rear facing camera kits that bond to an app on your smart phone. Even though this type of device is great at providing you with an actual live image of where you’re going, they can be expensive optional extras, unless you fit one yourself. They can also provide a limited view depending on the type of lens and placement of the camera. 

Electromagnetic Sensors are probably the not so common kind of parking sensor available on the market. Installed behind the bumper itself, they work by creating an electromagnetic field around the rear of the vehicle and sound a warning when it senses a disturbance within the electromagnetic field. We hope this clears up any questions you might have about car sensors and gives you a little more to go on the next time a mechanic or service writer talks to you about your illuminated check engine light!

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