The Sunday News
Modern cars are very complicated with so much technology that is meant to make the car run smoothly and more efficiently.
This technology is good when one understands it, sometimes it’s a menace when it packs up and you do not even know where to look or what to touch. It’s become so advanced that a lot of the time you will need a diagnostic machine to find out exactly where the problem is.
All modern cars have ECUs — engine control units and various sensors that read and report to the ECU — it’s like a organogram with every one of them with its own specific function and reporting to the ECU. Here are some of the sensors and their functions. There are many others but these are the most common.
Speed sensor
The speed sensor detects the speed of the vehicle and feeds information to the vehicle computer. When it goes bad you may not be able to tell the speed but there are other greater problems that crop up because of a bad speed sensor. There are many types of speed sensors and all cars are made differently but problems may be the same.
Faulty speed sensors may cause the transmission to misbehave since the ECU won’t be able to read correct speed. A diagnostic check whenever you see the engine check light is important to determine where the problem really is.
Coolant temperature sensor
This is an important sensor found in all combustion engines and monitors the engine temperature.
It sends signals to the ECU to adjust a lot of things depending on engine temperature reading. Most cars with ECUs usually rev higher when cold so as to warm up the engine. When the engine is cold the ecu sends a signal for delivery of a richer fuel mixture which leans out as the engine gets hot. The coolant sensor is the one at work sending signals to adjust the fuel delivery and all. Modern cars also cut when the engine overheats. Again the signal comes from the coolant temperature sensor. It reports when engine temperature is cold, optimum or too hot.
The cooling fan on the other hand is set to come on when the engine gets hot. Faulty sensors may mean the fan won’t come on when supposed to or vice versa.
Oxygen sensor
Most cars produced from the 80s have oxygen sensors. An oxygen sensor is located on the exhaust manifold and its primary function is to make sure the engine runs as efficiently as possible with minimal exhaust emissions.
This sensor feeds information to the ECU so that there can be a correct air and fuel ratio for complete combustion. When it completes its job, the end result is lower emissions and maximum engine efficiency.
Camshaft position sensor
The camshaft position sensor collects information about camshaft speed and piston position. This sensor is essential for ignition and injector timing. When it goes bad for whatever reason you may have no ignition at all. When it’s going bad usually it causes poor idling, stalling and surfacing of the dreaded engine check light.
Crankshaft position sensor
Like the camshaft position sensor, the crankshaft position sensor sends information to the ECU about the rotational speed of the crankshaft so the ECU can determine fuel delivery and spark timing.
It’s an important sensor for ignition timing and fuel delivery, when it’s faulty and sends wrong information you may have serious engine trouble in the form of misfire and acceleration problems as well as increased fuel consumption.
In worst cases, your engine might not start at all if the sensor has gone bad since it’s also responsible for ignition timing.
Mass Airflow sensor MAF
The Mass airflow sensor monitors the volume of air going into the engine and is usually located between the air filter box and the intake manifold.
These sensors are equally important where engine performance is concerned. They can get dirty or clogged over time if your filter is not doing a good enough job in filtering the air. It’s good to always keep a clean air filter and replacing worn out or dirty filters. A bad MAF sensor can cause idling problems, misfire, poor fuel economy etc. Disconnecting the Mass airflow sensor and checking it is easy as long as you do not temper with the wire inside. Usually quick drying cleaning sprays do a good job cleaning these sensors.
Knock sensor
It seems self explanatory, its primary function is to detect engine vibrations caused by a knock or detonation. Detonation can be very costly because it can damage engine components.
This is when there is pre-ignition before the piston reaches scheduled spark ignition and this action will try to reverse the direction of the piston and engine. This knock sensor sends signals to prevent denotation or to alter ignition timing to prevent detonation.
Faulty sensors send wrong signals or no signals at all and can cause problems like high fuel consumption, engine misfire, cutting out etc.
Some sensors actually control vital functions like ignition timing and without them working as they should your car will not even start.
There’s no guess work in modern cars, when the engine check light comes on, bring it for diagnosis. We will look at other sensors next time. Happy Motoring!
@lovert116 – Automart Used Spares Centre – Quality Used Japanese Spares -+263 772 33 99 38 – [email protected] – Facebook: @automartusc
