What are engine sensors? What is the purpose of sensors in vehicles? What sensor can be used to detect which engine fault?
Computers are only capable of performing the tasks that they are programmed for. An engine control computer for a vehicle (also known as an ECU or Powertrain Control Module) is programmed so it can act on data received from various sensors. These sensors are the engine’s eyes and ears. These sensors are essential for ensuring that the vehicle is running in the best conditions. The motor can malfunction if the received signal or data is lost.
The PCM will get less fuel mileage if it cannot receive signals from the oxygen sensor and coolant temperature sensors. The PCM won’t be able adjust the fuel mixture properly if it does not receive the correct data from the throttle sensor, MAP sensor, and air flow sensors. If the crankshaft position sensor is not working, the engine might not start.
Sensors. It monitors the following functions: ignition timing, fuel delivery (emission controls), transmission shifting and cruise control, as well as engine torque reduction (if there are anti-lock brakes that include traction control), the alternator’s charge output.
Let’s have a look at these sensors.
Sensor to measure engine coolant temperature
The engine coolant temperature is monitored by the coolant sensor. It can be found on the intake manifold or cylinder head. The coolant temperature affects the resistance. This sensor sends data to the PCM. Based on the engine’s temperature, the PCM determines how much fuel to send and sends necessary signals to other emission function.
The coolant sensor can be a crucial sensor. It can cause the radiator fan to stop working if it fails. It can cause excessive heat and expensive repairs. It can cause a rich fuel mixture and excessive fuel consumption.
Oxygen Sensor
Since 1981, the oxygen (O2) sensor has been part of both fuel-injected and carburetor engines. It is used to measure the mixture of air and exhaust gas. Some vehicles have one sensor, while others may have two.
The O2 sensor produces a voltage signal proportional the amount of unburned Oxygen in the exhaust. The engine will burn most of its oxygen if it has a rich mixture. The exhaust oxygen level is therefore low. These differences can be measured by the sensor, and then reported to the computer. The PCM uses these data to rebalance fuel mixture.
The PCM increases the injectors’ time to increase the mixture of fuel and mixture when it is “lean mixture”. It reverses this process and reduces injector open time when it is “rich mixture”. The ideal mixture of fuel and air will give you the best performance, lowest fuel consumption, and lowest exhaust emissions.
OBD II-equipped vehicles are expected to last 150 000 km before their oxygen sensors need to be replaced. Due to pollutants in the exhaust, these sensors can wear out and become unusable over time. The sensor may not respond quickly to changes in fuel mixture or air if it is contaminated. False readings may also occur. This can lead to delays or errors in the PCM’s adjustment for the fuel/air ratio.
Research by the EPA (Environmental Protection Agency), has shown that 70% of vehicles that fail to pass the exhaust emission test require a new oxygen sensor.
Absolute Pressure Sensor (MAP).
To monitor the intake vacuum, the MAP sensor is installed in the intake manifold. The manifold pressure affects the frequency and voltage of the MAP sensor. This information is used by the PCM to determine motor load. The PCM can adjust the ignition timing or the amount of fuel that is sent to the injectors according to your needs.
The engine will still run if the MAP sensor is defective, but performance will be severely affected. It can also be observed sudden acceleration, cutoff, idling irregularities and jolting. This could also lead to the engine fault lamp turning on.
The vacuum hose that connects the sensor to the intake manifold must be checked before replacing a suspect MAP sensor. The sensor will not produce the correct signal if there is any blockage, looseness, or leakage. The MAP sensor may also be affected if the engine is leaking air.
Throttle Position / Position Sensor
This sensor, which is attached to the throttle body, measures the throttle position and sends it to the computer. This information is used by the PCM to determine engine load, acceleration, deceleration and idle status. The sensor data allows the PCM the ability to adjust injector timing and fuel/air mixture.
TPS sensor malfunction symptoms can often be mistaken for Map sensor. The engine will still run even if the sensor is damaged, but it performs poorly.
Mass Air Flow Sensors (MAF)
The MAF sensor is mounted in front of your throttle body and calculates the air mass entering your engine. The sensor measures airflow and density using a hot filament or a hot wire. Based on the intake air pressure or the volume of air sucked into the engine, the PCM calculates its load.
When the sensor is damaged or fails, the engine will continue to run. There are symptoms like fluctuations in engine idling, sudden acceleration interruptions, stopping, excessive fuel consumption and difficulty working. Cleaning the sensor can solve all these problems.
Air Flow Sensor
It is used in multi-point electronic gasoline injection engines. It informs the PCM how much fuel is being injected into the engine. This data can be compared to data from other sensors. The PCM determines the ON and OFF times for injectors in order to determine the fuel amount. The fault symptoms for the MAF sensor are the same.
Manifold Air Temperature Sensing (MAT)
This sensor is located on the intake manifold. It measures the temperature in the engine’s air and reports it back to the PCM. The engine control unit calculates the fuel amount to be injected by injectors and determines how much air-oxygen is entering the combustion chamber.
The MAT sensor will fail if the fuel/air mixture is not correctly calculated and the engine will be run in a lean or rich mixture.
Crankshaft Speed Sensor (CKP)
The crankshaft location sensor, which is used in engines with distributorless-ignition systems, regulates ignition and fuel injection. It sends a signal to the PCM to determine the position of the first cylinder’s piston. This information is necessary to control the timing of ignition and the operation the fuel injectors. The signal from crank sensor tells the PCM how fast engine is running (engine speed). As such, the timing of the ignition is adjusted to suit your needs. Some engines use a separate camshaft position sensor in order to assist the PCM in determining the correct ignition pattern.
This sensor can fail, and the engine will not start if it fails.
Knock Sensor
The knock sensor detects vibrations and knocks in the engine, and reports them to the PCM. The PCM then adjusts the ignition and injector advance based on this information. Two knock sensors are available for some engines.
The knock sensor may fail, and the PCM won’t be able adjust the ignition timing. Excessive vibration in the engine could cause detonation. Excessive knocking will cause damage to the pistons and valves as well as bearings, bearings, cylinders, and other parts. You will notice symptoms like stalling, low performance, high fuel, and engine shaking.
Barometric Pressure Sensor – BARO
The barometer sensor measures the barometric pressure. This task is also performed by some MAP sensors. Weather and altitude affect the atmospheric pressure. The pressure drops as the density of air decreases at higher altitudes. This sensor compensates the engine’s operation at high altitudes. The PCM detects atmospheric pressure changes and adjusts fuel mixture and injector timings.
Speed Sensor (VSS).
The vehicle speed sensor (or VSS) monitors vehicle speed. The PCM monitors vehicle speed, mileage and gear changes. Cruise control can also be controlled by it. Many devices can be controlled by the PCM. This sensor can be found in the transmission, differential or gearbox. In some vehicles the ABS wheel speed sensors do the work of the speed sensor within the gearbox.
The vehicle’s speed sensor could malfunction, causing it to lose its cruise control. It can also affect the ability to change gears.
These electronic parts are very expensive and can be found in the sensors of your vehicle. The other fault codes should also be checked before changing the sensor. You will waste your money and the sensor won’t work.
