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This Week's Most Popular Stories About Audi G28 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 at the edge of transmission over the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indicator 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 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 show the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging as there are two different connector pins and they have different functions but the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is functional, it should read approximately 1000 ohms. Check for new audi car key of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive drop in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs. Three were soaked with gazoline and the fourth one was dry. When i crank the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th one stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. I assume that the problem is in another location.

I also tried to reset the PID but without success. The car will start if the G28 is not plugged in and it runs perfectly 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 a temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar when 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. I'm afraid i may have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate 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 to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.

4. ECU

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


Some of the signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or misfiring when you're in gear. If you have any of these issues it is most likely that your sensor is going bad and requires replacement. The good news is that they are very cheap and easy to find, especially if you're looking at an Bosch unit which is what ours are. If you prefer, GM's version of this part is an option.

5. Tachometer

A failing engine speed sensor could be the reason behind numerous issues in your car. It's a vital component of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it will disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to control fuel, timig, and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can test for sensor failure by checking 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 [79trace [79]), and between pin T6a/1 and pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU, so you might find them in wrecking yards.