Engine Sensors Explained ~ How They Work, Location, and OBD2 Code

In this video, every single car engine sensor is explained. For each sensor we’ll be explaining what it does, how does it do it, where is the sensor location and what happens if the sensor goes bad. There are also OBD2 error codes for all the sensors. For example: P0335, P0118, P0131, P0340, P0300, P0102, P0113, etc.

• Related: OBD / OBD-II Diagnostic Trouble Code Database

So the next time you have a problem with one of your sensors you will know what’s happening, why is it happening, where is the sensor, and what will happen if you don’t fix it.

To make the video simple and logical its been grouped into 5 sensor categories.

1. Position Sensors (crankshaft position sensor, camshaft position sensor, throttle position sensor)
2. Air flow Sensors (mass air flow sensor MAF, vane air flow meter)
3. Pressure Sensors (MAP or manifold absolute pressure sensor, oil pressure sensor, fuel pressure sensor)
4. Temperature Sensors (IAT or intake air temperature sensor, coolant temperature sensor, fuel temperature sensor, oil temperature sensor)
5. Air Fuel Ratios, Emissions and Others (oxygen 02 sensor both wide band and narrow band, egt or exhaust gas temperature sensor, nitrogen oxide or nox sensor for SCR selective catalyst reduction and the knock sensor)

We’ll see how each sensor communicates with the ECU and how each sensor is a piece of the puzzle. When they all work together correctly, the ECU gets to see the big picture and accurately and efficiently manage the operation of the engine.

For example, the crankshaft position sensor tells the ECU where the piston is so the ECU knows WHEN to inject the fuel. Airflow sensors like the Mass airflow sensor or the map sensor tell the ECU how much air is coming into the engine so the ECU knows HOW MUCH fuel to inject. The throttle position sensor and the intake air temperature sensor tell the ECU the load placed on the engine and the intake air temp which further improves the accuracy of the injection.

The final stream of information necessary for injection accuracy comes from the fuel pressure sensor which lets the ECU calculate exactly how long it needs to keep the injectors open in order to deliver the precise quantity of fuel needed.

In case something does go wrong, we have the lifesaver sensors like the knock or oil pressure sensors. The knock sensor listens for knock or abnormal combustion and if it detects it warns the ECU and the ECU in a matter of milliseconds retards ignition timing and/or adds fuel to prevent knock from occurring again.

The oil pressure and oil temperature sensors make sure that the engine oil, the lifeblood of the engine, is within functional parameters. As soon as it even briefly drifts out of expected values the ECU can protect the engine and warn the driver.

All in all modern cars (and engine swapped hot rods) are a moving world of information where a large number of sensors rapidly provides endless amounts of data that gets interpreted at lightning speeds by the ECU where it triggers a sea of different actions that keep you moving smoothly and safely along the road all while preserving efficiency and minimizing emissions.

Engine Sensors Explained

• 00:57 Crankshaft position sensor
• 02:54 Camshaft position sensor
• 03:58 Throttle position sensor TPS
• 05:44 Mass air flow sensor MAF
• 07:39 Vane air flow meter AFM
• 08:44 Manifold absolute pressure sensor MAP
• 10:27 Oil pressure sensor
• 11:55 Fuel pressure sensor
• 12:34 Intake air temperature sensor IAT
• 14:09 Coolant temperature sensor
• 15:22 Fuel temperature sensor
• 16:16 Oil temperature sensor
• 17:24 Oxygen 02 sensor
• 20:18 Exhaust gas temperature sensor EGT
• 22:05 Nitrogen oxide sensor NOx
• 23:01 Knock sensor
• 24:07 Quick recap of key sensors