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25 Surprising Facts About Audi G28
How to Replace an Audi G28 Engine Speed Sensor

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

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU uses this information to control fuel and boost. It also sends an indicator to the G5 Tachometer within the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors according to the situation.

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 the chain stretching or a jump link on the upper chain of timing. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).

It can be a bit difficult to test because there are different pins on the connector and they all have different 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 read around 1000 ohms. If you're experiencing issues with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had an abrupt drop in power like the engine is running out of gas or injectors aren't firing at all. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was unclean. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I think the issue is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do. I think I've eliminated everything else. But visit the following website page '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 can be activated by a signal sent by the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. It is simple to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite ohms.

4. ECU


Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that has to know the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

A damaged G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire in gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these symptoms. They're inexpensive and easy to locate, especially in the case of an Bosch model like ours. Alternately, the GM version of this component is also a great option.

5. Tachometer

A failing engine speed sensor could be the cause of a slew of problems in your vehicle. It is an important part of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine is spinning. If the sensor fails, it could cause problems for the transmission as well as the rest of the car's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. You can also check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should see a resistance of approximately 1000 ohms in these areas. This is a standard component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.

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