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15 Up-And-Coming Trends About Audi G28
How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, just above the flywheel ring. This 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 an indicator to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors according to the situation.

If this sensor fails, the ECU will display a P00160 code 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 timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).

It is a little tricky to test since there are various pins on the connector, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should read approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, as i was accelerating off the 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. Today, i pulled out the spark plugs, three were soaked with gazoline and the fourth was dry. When i crank the engine without sparks i put tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stays shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. audi keys 'm assuming that the issue is in another location.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected and runs fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. Also i 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 certain what to do, i feel i have pretty much completely ruled out all other possibilities. But i am afraid I may have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sensor is identical to the G4 and they both work 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 - simply put your DMM into resistance mode and test 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 are equipped with an ECU that needs to know the position and speed of the crankshaft in order to make decisions about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down.

A failing G28 sensor could result in an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. If you have any of these problems, it is most likely that your sensor is failing and needs replacing. The good thing is that they are very cheap and easily accessible particularly if you're looking at a Bosch sensor, which is what we have. If you prefer, GM's version of this component is a good option.


5. Tachometer

A faulty engine speed sensor could be the reason behind many issues with your vehicle. It is a crucial part of your Audi's transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins 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. It should show approximately 1000 ohms of resistance between those points. This is the same across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU So, you may find some good ones in wrecking yards.

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