This Is The Ultimate Cheat Sheet On Audi G28

How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located near the transmission's edge just above the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through a grey wire. The ECU uses this information to regulate fuel and boost. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.
If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
It's a bit tricky to test since there are various connector pins, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is at full operation. If you're experiencing issues with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss like the engine is out of gas or injectors are not firing any more. Today, i pulled out the spark plugs. Three were drenched in gazoline, the fourth one was dry. I put tissue over each injector hole and when I start the engine with no sparks, the three with gazoline jump out. The 4th one remains shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However, audi q7 keys locked in car persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I don't know what to do. I believe that I've eliminated everything else. But i am afraid I may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives 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 the spare in a salvage shop or a parts store. It is simple to test them - simply switch 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 should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft to determine timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down.
A failing G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. If you experience any of these issues it is most likely that your sensor is going bad and should be replaced. They are cheap and easy-to-find especially in the case of a Bosch sensor like ours. Alternatively, GM's version of this component is an excellent choice.
5. Tachometer
A damaged engine sensor could cause a myriad of issues in your vehicle. It's a vital component of your Audi's transmission, because it communicates to the ECU about how the car's crankshaft is spinning. When this sensor fails, it could disrupt the performance of the transmission as well as the other car's components.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU is then able to process the signal to control fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 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 the 1995 RS2 DU You may also find good ones in wrecking yards.