What Do You Think? Heck What Exactly Is Audi G28? How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located near the transmission's edge over the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.


If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test because there are different pins on the connector, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is operating at its maximum. Examine for signs of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, three were soaked with gazoline and the fourth one was dry. When I crank the engine without sparks i put tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is in another place.

I also tried to reset PID but without success. The car can start if the G28 is disconnected and runs fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, as i believe that i've completely ruled out all other possibilities. But i'm worried that i might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. It is simple to test them to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these sensors, the diagnostic scanner will display codes that could lead to the engine shutting down.

Some of the symptoms of a failing G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you're in gear. If you are experiencing any of these issues, it is most likely that your sensor is failing and should be replaced. They're cheap and easy to find especially in the case of a Bosch sensor like ours. Alternately, the GM version of this part is also a great option.

5. Tachometer

A faulty engine speed sensor could be a cause for a slew of issues with your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how the car's crankshaft is turning. When this sensor fails, it could cause problems for the transmission and the rest of the car's components.

The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. audi battery key replacement to control the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms of resistance between these two points. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.