Cars have sensors all over them. They are used to keep an eye on different things. Most of these sensors are in the engine. They help in checking specific parts and sending information to the engine control unit (ECU). The ECU then uses this data to adjust how the engine runs, making sure it works efficiently.
So, what do these sensors do, and how do they work? In this article, we’ll go over the key engine sensors, explain what each one does, and how to know if they’re not working right.
Purpose Of Car Sensors?
Car sensors are mainly for “sensing” and “monitoring,” just like their names say. The main job of these sensors is to collect data and send it to the Electronic Control System (ECS).
The ECS uses this info to help make decisions and take actions when needed. These sensors and the ECS turn physical and chemical changes into electric signals, letting the driver know if there’s something extra they need to do.
Working Of Car Sensors?
Think of car sensors like the human body senses. Our sensory organs help us stay aware of our surroundings and respond to changes. If something unexpected happens, our body tells our brain.
Car sensors work in the same way. They keep track of what’s going on inside the car. They will alert you if there’s a problem or something is blocking the way. Thanks to computers and new algorithms, these sensors are now more accurate.
When a car sensor detects an issue, it sends a signal to the car’s computer. The computer then alerts you by blinking dashboard lights and starts making sounds. Sometimes, the car might even take immediate action by itself if needed.
For example, the fuel level sensor in your car tells you how much gas is left. If you’re running low on fuel, it will bring to your notice. It can also alert you if there’s an issue with fuel drainage. Modern cars even use GPS along with the fuel sensor which improve the driving experience.
Types OF Car Sensors
Oxygen Sensor
Function
The oxygen sensor checks how much unburnt oxygen is in the exhaust gases. This helps to see if the engine is burning fuel efficiently.
- If there’s a lot of unburnt oxygen, the engine is running lean, meaning it needs more fuel in the mix.
- If there’s little unburnt oxygen, the engine is running rich, meaning there’s too much fuel in the mix.
Oxygen sensors are crucial in modern cars because the ECU (engine control unit) doesn’t always know the right fuel mix due to changes in load, altitude, and humidity. Oxygen sensors help the ECU adjust the fuel mix correctly.
Location
Most cars have two oxygen sensors in the exhaust system. One is placed before the catalytic converter, and the other is placed after it.
Faulty Oxygen Sensor Symptoms
If your check engine light comes on, it might mean you need to replace your oxygen sensor. Other signs include rough idling, misfires, lack of power, and stalling. These issues are noticeable. They can damage your engine if not fixed.
A bad oxygen sensor also hurts fuel efficiency. The Environmental Protection Agency says replacing a broken oxygen sensor can improve fuel economy by up to 40%. Additionally, with a faulty oxygen sensor, your car will likely fail an emissions test.
Lifespan
The sensor is designed to last as long as your car, but it can sometimes fail early.
OBD-II Trouble Codes
Mass Air Flow Sensor
Function
The mass airflow sensor (MAF) measures how much air enters the engine. It heats a small wire with electricity and then passes air around it. As more air flows, the wire cools down. This creates a larger requirement of more electrical current to keep it hot. The amount of current needed is proportional to the airflow. This gives the ECU an estimate of the air entering the engine.
This information helps the ECU balance and deliver the right amount of fuel to the engine. It aims for an optimal fuel-to-air ratio in the combustion chamber.
Location
The MAF sensor is usually positioned after the air filter and before the intake manifold of the engine.
Faulty Mass Air Flow Symptoms
A dirty or faulty mass air flow (MAF) sensor can cause the ECU to get incorrect readings. This disrupts the engine’s ability to maintain the optimal fuel-to-air ratio. You might notice symptoms like difficulty in starting, stalling, poor acceleration, rough idle, reduced fuel efficiency, and black exhaust smoke. The check engine light may also come on.
Additionally, the MAF sensor can affect the vehicle’s automatic transmission shifts. If there’s an issue with the MAF sensor, the transmission might shift earlier or later than usual within its rev range.
Lifespan
The MAF sensor is designed to last as long as your car, but occasionally it can fail before its expected lifespan.
OBD-II Trouble Codes
Oil Pressure Sensor
Function
Oil needs to flow through all parts of the engine. This helps to lubricate the engine parts properly. Without enough pressurized engine oil, the engine can overheat and suffer damage. The oil pressure sensor alerts you if your vehicle isn’t maintaining the necessary oil pressure.
The sensor sends signals to the oil pressure light on your dashboard. If the oil pressure is too high or too low, the light will come on. This helps prevent serious engine problems and keeps your car running smoothly.
Location
The oil pressure sensor is usually found between the oil filter and the oil pan, typically on the bottom right side of your engine.
Faulty Oil Pressure Sensor Symptoms
If your oil pressure sensor light comes on, it can be due to two reasons. Either a faulty sensor or actual low oil pressure. To fix this, an automotive technician can use a mechanical gauge to measure the engine’s real-time oil pressure accurately. This helps to identify whether there’s a sensor issue or a genuine problem with oil pressure levels.
Lifespan
The oil pressure sensor is designed to last as long as your car, but occasional premature failure can occur.
OBD-II Trouble Codes
Throttle Position Sensor
Function
The throttle valve regulates the amount of air entering the engine’s intake manifold. Throttle position sensors (TPS) monitor the position of the throttle valve. This corresponds to how much the accelerator pedal is pressed by the driver. This data is important for maintaining the right fuel-to-air ratio in the engine.
In addition to fuel efficiency, this information is used by other vehicle systems like traction control, anti-lock brakes, and cruise control. This helps these systems to operate effectively based on the driver’s throttle input.
Location
The TPS is usually attached directly to the throttle valve, which is located at the top of the engine.
Throttle Position Sensor Symptoms
A faulty TPS can lead to misfires and stalling. In vehicles with electronic throttle control, a bad TPS might cause the vehicle to enter limp mode, reducing power. Fortunately, the check engine light will come on if the TPS fails.
OBD-II Trouble Codes
Coolant Temperature Sensor
Function
The engine coolant temperature sensor (ECTS or CTS) measures the temperature of the coolant in the engine. It helps to determine how much heat the engine is producing. It ensures how well the cooling system is working.
The ECTS detects temperature changes by measuring the voltage passing through it. The sensor’s resistance varies with temperature: less resistance when the coolant is hot. The ECU uses this temperature data to control functions like ignition timing and the radiator’s cooling fan speed.
Location
There is usually one ECT sensor located on the engine, and sometimes a secondary ECT sensor in the radiator.
Coolant Temperature Sensor Symptoms
A faulty ECT sensor can give incorrect coolant temperature readings, either too high or too low. Incorrect readings can cause the engine to perform poorly or have poor fuel economy. If the sensor shows a cool reading, the ECU will use a richer fuel-to-air ratio, which can cause black smoke from the exhaust. A lower reading will result in a leaner mix. A faulty sensor can also trigger the check engine light or cause your car to overheat.
OBD-II Trouble Codes
Knock Sensor
Function
Faulty ECT sensor can give incorrect coolant temperature readings. It will show either too high or too low reading. This can cause the engine to perform poorly. It may also lead to poor fuel economy. If the sensor shows a cool reading, the ECU will use a richer fuel-to-air ratio. This can cause black smoke from the exhaust. A lower reading will result in a leaner mix. A faulty sensor can also turn on the check engine light. It can also cause your car to overheat.
Engine knock is also called as detonation. It occurs due to abnormal combustion inside the engine. This can be very damaging. Knock sensors detect the distinct vibrations caused by this knocking noise. When a knock sensor identifies engine knock, it signals the ECU to adjust the ignition timing. This will reduce the knock and protect the engine.
Location
The knock sensor is usually attached to the outside of the engine block, but it can also be located underneath the intake manifold.
Coolant Temperature Sensor Symptoms
Without a working knock sensor, the ECU can’t adjust to stop engine knock. This can cause knocking or pinging noises and reduce your vehicle’s acceleration. The check engine light will likely come on. If engine knock continues due to a faulty sensor, it can damage internal engine components and potentially cause the engine to fail.
OBD-II Trouble Codes
Crankshaft/Camshaft Position Sensor
Function
The crankshaft and camshaft position sensors keeps track of the rotation and speed of the crankshaft and camshaft. They send this information to the ECU. The crankshaft converts the pistons’ linear motion into rotational force. This helps to propel the vehicle. The camshaft controls the opening and closing of the engine’s valves. Both must be synchronized for the engine to work properly.
These sensors use a reluctor ring with teeth that pass by the sensor tip as the shafts rotate. Magnets in the sensors detect these teeth. Since some teeth are missing to create a reference point, each tip corresponds to a specific position of the crankshaft or camshaft, which the ECU uses to maintain proper engine timing.
Location
The crankshaft position sensor is often located near the main pulley, at the transmission bell housing, or on the cylinder block.
Coolant Temperature Sensor Symptoms
If the crankshaft or camshaft position sensor fails completely, your engine may not start. Partial failure can lead to inconsistent signals sent to the ECU, resulting in issues like sudden engine shutdowns or difficulty starting your vehicle. A faulty sensor can also cause sudden stalls, inconsistent acceleration, and engine misfires. You may experience jerking, surging, and vibrations as the ECU injects the wrong amount of fuel due to incorrect camshaft position information. The check engine light on your dashboard will illuminate as well.
OBD-II Trouble Codes
P0336, P0339 (CKP) P0340 (CMP).
Conclusion
In today’s cars, sensors are essential for monitoring engine functions, adjusting fuel mixtures and timing, and ensuring optimal performance and efficiency. They play a critical role in maintaining reliability, improving fuel economy, and reducing emissions, making driving safer and more efficient.
