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10 Quick Tips About 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. This sensor is located on the edge of the transmission above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer located in the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft has reached TDC and also the position of the camshaft, in order to activate the spark and injectors.

If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper timing chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).

It's a bit tricky to test because there are several connector pins, and they all have different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is operating at its maximum. Examine for signs of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge reduction in power. It was like the engine had run out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. I placed a tissue over each injector hole and when I start the engine with no sparks, the 3 with gazoline jump out. The 4th one remains closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. So i assume the problem is elsewhere.


I also tried to reset the PID but without success. The car will start when the G28 is unplugged and runs fine when it is connected however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I don't know what to do. I think I've eliminated everything else. But i'm worried that I might have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works 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 - just switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions about timing of the fuel injector, for example. To accomplish audi key fob replacement , it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display codes that could lead to an engine shutdown.

Some of the signs of a failed G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you're in gear. It is possible that the sensor is failing and requires to be replaced if you experience any of these signs. The good news is that they are quite affordable and easy to find, especially in the case of an Bosch model, which is what we have. You can also choose the GM version of this unit is also a good option.

5. Tachometer

A failing engine speed sensor could be the cause of numerous issues with your car. It is a crucial part of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. When this sensor fails, it could disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to control fuel, timig, and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those two pins. This is a typical part across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.