Your Sensors worn out? » Read more about common malfunctions • Repair • Replacement manual
All systems at a glance, thanks to sensors
An extensive array of sensors is part of any modern vehicle. In addition to numerous tasks relating to engine management, they also perform many tasks for convenience functions. A sensor detects a change in environmental conditions and forwards this information to a control unit. This allows today's vehicles to offer far more efficiency and comfort than they previously could.
Optimum performance at minimum fuel consumption
Engine control is now no longer possible without a comprehensive sensor system. Intake air mass, emitted exhaust gas, oil, air and water temperatures, rotation speeds at the crankshaft or camshaft are all variables, which are important for the control unit. With millions of calculations per second, the electronic control unit constantly determines the exact amount of fuel necessary for achieving optimum performance with minimal fuel consumption. Typical sensors used for engine management include:
- the air mass meter (measures the quantity of intake air)
- the lambda probe (measures the amount of emitted oxygen in the exhaust gas)
- the rotation speed sensors at the crankshaft and the camshaft
- oil, air and coolant temperature sensors
- pressure sensors in oil and coolant
Safe driving thanks to sensors
Since 2014, tires must be equipped with tire pressure sensors in all new vehicles. While this is annoying and expensive, it is also a sensible contribution to vehicle safety. If the tire pressure drops more than 0.2 bar below the set value, the sensors will indicate this via a warning sign on the dashboard. Thus, the driver is left with enough reserves to inflate the tires at the next fuel stop.
In modern vehicles, light sensors notice entry into a dark area, such as a garage, an underpass or a tunnel. They also register nightfall and automatically switch on the vehicle lighting, if desired.
Rain sensors detect water falling onto the windshield and automatically activate the windshield-wiper system.
Maneuvering aids are particularly popular these days. They consist of radar sensors, which are installed in the rear bumper and in some cases also the front bumper. When approaching an obstacle, this proximity sensors trigger a warning. The next evolution of the proximity sensors can already be found today in the brake assist system. They independently actuate the brakes before a collision occurs. This significantly reduces the consequences of, or even completely avoids, accidents.
Yet, if a serious collision with an obstacle or a roll-over does occur, additional safety sensors are available to mitigate the consequences. Within microseconds, pressure and position sensors provide the necessary impulses for triggering the airbags.
Though slightly annoying, the pressure sensors in the vehicle seats are very effective. They trigger a warning until the passenger or the driver have put their seat belt on.
Fill level and pressure sensors aren't just important inside the fuel tank. They also inform the driver of overpressure in the coolant, or of insufficient pressure in the oil system or brake system. This pressure loss can be very dangerous, wherefore these sensors are very important.
A defective sensor is either immediately registered or results in a malfunction of the vehicle. High fuel consumption and weak performance are often the result of a defective mass air flow sensor or lambda sensor. As a vehicle's information system components, any defective sensor is registered by the control unit. The easiest way to detect a defective sensor is always reading the car's fault memory.
Repairing a sensor
Usually sensors are simply replaced rather than repaired. Really, the only thing that can be repaired on a sensor are the plug contacts. These can become corroded by moisture ingress. Here, the function of the sensor can be restored by grinding the contacts to clean them and then sealing them with some contact spray. However, this type of damage is rather seldom. In most cases, a sensor burns out, corrodes from the inside or is damaged by external influences. Air quantity sensors are an exception: These can often be cleared of deposits with the help of brake cleaner.
Quality of replacement sensors
If the sensor must be replaced, a genuine spare part is very important. Only manufacturer-approved products can meet the demanding tasks in a vehicle. Therefore, one should always care to opt for brand quality when purchasing a replacement sensor.