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"Ask Me Anything": Ten Answers To Your Questions 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 near the edges of the transmission above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. This sensor sends a signal via 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 in the instrument cluster.

The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC, and where the camshaft lies so that it can activate the spark and injectors.

If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain is stretched or a jump link on 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 since there are two connector pins and they have different functions but the best method to test it is by measuring resistance between the sensor and the ECU. If the sensor is functional, it should read approximately 1000 ohms. If you're having issues with this sensor, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. When i crank the engine with no sparks, I put a piece of tissue on top of each injector hole and the 3 that were drenched in gazoline pop out, but 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. I'm assuming the issue is elsewhere.

I also tried to reset the PID but without success. The car will start when the G28 is not plugged in and it runs perfectly when it is plugged in but it still has intermittent misfire issues at higher RPM. audi key replacement cost (G62), even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.

I don't know what to do. I think I've all other possibilities out. But i am afraid I may have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. Testing them is easy - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will display codes that could cause an engine shutdown.


Some of the symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal, and/or a misfire when you are in gear. It is likely that your 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 particularly if you're looking at the Bosch sensor, which is what we have. Alternatively, the GM version of this component is also a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your car. It is an important part of the transmission in your Audi since it sends information to the ECU regarding how fast or slow the car's engine is spinning. This sensor could cause the transmission to fail and other components in the car to be affected.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU is then able to process the signal to control fuel, timig and boost and then sends it on to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show approximately 1000 ohms of resistance between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find good ones in wrecking yards.

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