The History Of Audi G28 How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates 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 through a grey wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

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

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

If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jump in the chain link of the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).


Testing can be a bit difficult because there are two pins for the connector and they perform different functions however the best way to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should read around 1000 ohms. Check for signs of coolant, or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. I put a piece of tissue over each injector hole and when I start the engine with no sparks, the 3 with gazoline jump out. The fourth one remains shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found zero ohm. I assume that the problem is in another location.

I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. audi lost key replacement (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.

I'm not certain what to do, as i think i've pretty much ruled out everything else. I'm worried that i might have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. It is simple to test them - just switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these, the diagnostic scanner will display codes that could lead to an engine shut down.

The signs of a failing G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when in gear. It is probable that your sensor is failing and needs to be replaced if you encounter any of these signs. They're cheap and easy to find particularly when they're an Bosch sensor like ours. Alternatively, GM's version of this part would be an option.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous issues with your car. It's an essential component of the transmission in your Audi since it sends information to the ECU regarding how fast or slow the engine of the car is turning. When this sensor fails, it can affect the performance of the transmission as well as the other car's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should detect an average resistance of 1000 ohms between these points. This is a common part across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.