How to Replace an Audi G28 Engine Speed Sensor Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster. 1. Engine Speed Sensor The grey wire is situated on the outside of the transmission, above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster. The sensor is used to link the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors. If this sensor fails to function, the ECU will display a P00160 error code. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper chain of timing. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40). It's a bit tricky to test as there are various pins on the connector and they all have different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when it is at full operation. If you're having issues with this component, look for signs of coolant or oil 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 the injectors aren't firing any more. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth one was dry. When I start the engine without sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. So i assume the problem is in another place. I also tried to reset PID without success. The car will start when the G28 is disconnected and it runs perfectly when it is connected, but still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. 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 think i've pretty much ruled out everything else. But i am afraid i might have missed something. If anyone has any ideas please share them! TIA! 3. Fuel Pump The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). 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 position and speed of the crankshaft to make a decision about timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If https://www.openlearning.com/u/katzhale-ski1jc/blog/WhatAreTheBiggestMythsAboutReplacementAudiKeyCouldActuallyBeTrue of these sensors go wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down. A damaged G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, or a misfire in the gear. If you are experiencing any of these issues it is likely that your sensor is failing and requires replacement. They're cheap and easy to find especially in the case of a Bosch sensor like ours. You can also choose the GM version of this component is also a good choice. 5. Tachometer A malfunctioning engine speed sensor could be a cause for numerous issues with your vehicle. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. When this sensor fails, it can cause problems for the transmission as well as the other car's components. The G5 engine speed sensor is located on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via a grey wire. The ECU is then able to process this signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. There should be the resistance to be around 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 So, you may find good ones in wrecking yards.