How to Replace an audi replacement key service G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

It is a little tricky to test as there are different pins on the connector and each has its own functions. The best way to do it is by measuring the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Examine for signs of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stay shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. So i assume the problem is in another place.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.