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 near the edges of the transmission just above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49), then 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 a signal to ECU pin T55/49 via an uncolored wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster. The sensor is used to connect the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly. If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jump in the chain link of the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40). Testing is a bit challenging as there are two different pins for the connector and they perform 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 around 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are problems with this part. 2. Injectors Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a significant decrease in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. https://notes.io/w27U4 took out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. I placed a tissue over each injector hole and when i start the engine without sparks, the three with gazoline jump out. The 4th one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero Ohm. Therefore, i think the issue is in another place. I also tried to reset the PID but without success. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. Also i noticed that the gauge for oil pressure 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, but i believe that i've ruled out everything else. But i am afraid I may have missed something. If anyone has suggestions, please let me know! TIA! 3. Fuel Pump The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sender 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 junkyard or from a parts store. It is simple to test them - just switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite ohms. 4. ECU The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go badly, you will see codes on the diagnostic scanner that could cause engine shut down. The signs of a malfunctioning G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when you are in gear. It is probable that your sensor is failing and needs to be replaced if you encounter any of these signs. They are cheap and easy-to-find especially when they're an Bosch unit like ours. Alternatively, GM's version of this part would be an excellent choice. 5. Tachometer A failing engine speed sensor could be the cause of numerous issues with your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU about how fast or slowly the engine of the car is turning. If the sensor fails, it will affect the performance of the transmission and the rest of the car's components. The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between these two points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find them in wrecking yards.