Camshaft position sensor G40. 1.9 TDI PD from VAG Group. Family of diesel engines with injection pump-injector

Camshaft position sensor G40

The camshaft position sensor G40 is a Hall sensor. It is attached to the protection of the timing belt under the camshaft gear; scans seven teeth on the camshaft sensor wheel attached to the camshaft gear.

Signal application

The J248 Direct Fuel Injection Engine Control Module uses a signal generated by the camshaft position sensor G40 to determine the relative position of the pistons in the cylinders when starting the engine.

Consequences of signal failure

In the event of a failure of the camshaft position sensor signal G40, the direct fuel injection engine control module J248 uses a signal generated by the engine speed sensor G28.

Electrical circuit

G40 Camshaft position sensor
J248 Direct fuel injection engine control module
J317 Power supply (terminal 30, B +) Relay.

Recognition of the cylinder when starting the engine

When starting the engine, the J248 Direct Fuel Injection Engine Control Module must determine which cylinder is in compression stroke to activate the correct injector valve. To achieve this, it evaluates the signal generated by the camshaft position sensor G40, which scans the camshaft sensor wheel teeth to determine the camshaft position.

Camshaft sensor wheel

Because the camshaft rotates 360 degrees per duty cycle, there is a tooth on the sensor wheel for each individual cylinder. These teeth are located at a distance of 90 degrees from each other. To distinguish the cylinder, the sensor wheel has an additional tooth with a different interval for each of the cylinders 1, 2 and 3.

Each time the tooth passes through the camshaft position sensor G40, the Hall effect voltage is induced and transmitted to the J248 direct fuel injection engine control module. Because the teeth are located at different distances from each other, the induced voltage occurs at different intervals. Based on this, the direct fuel injection diesel engine control module J248 determines the relative position of the cylinders and uses this information to control the solenoid valves of the injector pump.

Read more about the family of diesel engines with injection pump-injector here .