Top Picks For Engine Sensors & Switches Related Parts

New vehicles today are equipped with various sensors and advanced electronic systems that improve the operating conditions and performance of the vehicle. Engine sensors like Mass Air Flow (MAF) sensor, engine knock sensor, crankshaft position sensor, oxygen sensor, throttle position sensor, etc. work together and send the important data to the Electronic control unit (ECU). The ECU, with the help of these sensors, controls almost every aspect of the engine to deliver excellent performance, good fuel economy, and reduced emissions. Other than sensors, the electronic circuitry of an automobile comprises switches and relays as well. Relays are switches controlled by electric power and their purpose is to switch electrical circuits on and off at particular times.

An oxygen sensor, also known as a lambda sensor, reads the oxygen content in the exhaust gas and sends the data to the engine's computer. This data allows the engine control module (ECM) to know whether the engine is running on rich (more fuel and less air) or lean (less fuel and more air) air-fuel mixture and the ECM accordingly adjusts fuel delivery to maintain an ideal air-fuel mixture. This results in reduced emissions and increased engine performance and fuel efficiency. The oxygen sensor is located just before the catalytic converter and helps in maintaining an ideal air-fuel mixture, which allows the catalytic converter to treat the exhaust gases properly. Modern vehicles are equipped with two oxygen sensors, one before (upstream) and one after (downstream) the catalytic converter. The two oxygen sensors allow the ECM to compare the oxygen content in the exhaust gases entering and exiting the catalytic converter, which, if similar, indicates an inefficient catalytic converter.

An oxygen sensor is a critical component of the emission control system of your vehicle and any fault in the sensor will send incorrect data to the engine computer, which can cause poor fuel economy, higher emissions, and an overheated catalytic converter. One common symptom of a faulty oxygen sensor is a check engine light on the dashboard. To determine if the oxygen sensor is faulty, you'll have to carry out an oxygen sensor diagnosis procedure. Few other signs that could indicate oxygen sensor malfunction are rough idle, misfiring spark plugs, lack of power, stalling, and low fuel economy. If you notice a check engine light along with the aforementioned symptoms, your oxygen sensor might need a replacement.

Knock sensors are used on the engine of the vehicle to sense unwanted vibrations and sounds that occur within the combustion chamber due to uncontrolled ignition timing to air-fuel mixture explosion. When the spark plug ignites the air-fuel mixture inside the combustion chamber, a flame front is formed, which gradually combusts the whole mixture inside the chamber. Sometimes, excessively high temperatures and pressure can cause the air-fuel mixture to auto-ignite and detonate. This sends pressure waves across the chamber and against the original flame front, causing a sudden spike in vibrations and noise which can damage the engine and its components. The knock sensor picks up on these vibrations and signals the ECU, which regulates the ignition timing accordingly. The knock sensor is directly attached to the engine block and is made using piezoelectric ceramic or elements that convert a mechanical effect, like vibrations, into electrical signals.

The knock sensor is exposed to harsh conditions and extreme temperatures. Apart from these factors the sensor can malfunction or fail due to physical damage like corrosion, short circuit, improper mounting, or mechanical injury while servicing the vehicle. Furthermore, any kind of accretion, like carbon build-up on the sensor, can also cause the knock sensor to fail. A bad knock sensor will show symptoms like poor acceleration, decreased engine performance, knocking or pinging noises, and will cause the check engine light on your console to come up. If you notice similar symptoms on your vehicle, you should verify the sensor's wiring connections, look for any damage and read out the fault codes related to the sensor and get it replaced.

Air mass sensor or mass airflow (MAF) sensor is an important component used in fuel-injected vehicles and is installed after the air filter and before the intake manifold. The purpose of an air mass sensor is to measure the amount of air entering the engine and send the data to the electronic control unit (ECU) which regulates the amount of fuel supplied and maintains an ideal air-fuel mixture. The air mass sensors are very helpful in measuring accurate air quantity because changing attitudes, forced inductions and temperatures can significantly alter the density and mass of the air entering the engine. Most vehicles use hot-wire type air mass sensors because they have a quick response time, are smaller, and are very durable.

A failing air mass sensor won't be able to calculate the correct amount of air entering the engine, which can lead to a disrupted air/fuel ratio leading to problems like detonation in the combustion chamber. If your vehicle's air mass sensor malfunctions or fails, it will show symptoms like poor driveability, engine jerks during acceleration, and bad engine idling. Additionally, a faulty air mass sensor can also light up the check engine light on the dashboard. Often the solution of a malfunctioning sensor may be as simple as cleaning the contamination off the sensor, but it's important to get your sensor checked for damage and get it replaced if you notice the aforementioned symptoms.  

The manifold air pressure (MAP) sensor is connected to the intake manifold of a fuel-injected engine. With different engine speed loads, the MAP sensor senses the absolute pressure change in the intake manifold and converts the change in the internal resistance of the sensor into a voltage signal for the ECU. Based on this signal, the ECU adjusts the fuel injection volume for optimum combustion. In naturally aspirated engines, the sensor detects a negative pressure found in the intake manifold, which we call a vacuum, whereas, in a forced-induction engine, the MAP sensor detects vacuum and the positive pressure generated in the manifold as well. The MAP sensor acts as an indirect way of calculating air density and determining the engine's mass flow rate for the ECU to meter the fuel accordingly. Typically, a naturally aspirated engine would use either a Mass Air Flow (MAF) sensor or MAP sensor to detect the airflow, but turbocharged or supercharged engines use both MAP and MAF sensors.

Like most electric sensors, the MAP sensor is sensitive to contamination and can fail. Often the electrical connection can loosen, crack or melt from overheating because of its proximity to the engine. A faulty MAP sensor will disrupt the air-fuel ratio, robbing the engine of its power and causing it to run poorly. It can also lead to symptoms like detonation, misfiring, failed emission tests, rough idling, engine stalling, and a check engine light. If you see a check engine light and suspect the MAP sensor is at fault, a sure way to check is to read the error codes using an OBD2 (onboard diagnostics) device. Avoid the hassle of carrying out major repairs on your engine by replacing the faulty MAP sensor, if you are experiencing the above-mentioned symptoms.