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How to Replace an Audi G28 Engine Speed Sensor Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49), then to the tachometer in the instrument cluster. 1. Engine Speed Sensor Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster. The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors according to the situation. If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper timing chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40). It is a little tricky to test as there are various pins on the connector, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is functional, it should read around 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you have problems with this part. 2. Injectors Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or, my injectors weren't firing. This morning i pull out the spark plugs, 3 were drenched with gazoline the fourth one was dry. I put a piece of tissue over each hole in the injector and when I start the engine without sparks, the three with gazoline jump right out. The 4th one remains closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got 0ohm. Therefore, i think the issue is elsewhere. I also tried to reset the PID without success. The car can start if the G28 is disconnected and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero. I'm not certain what to do, but i believe that i've completely ruled out all other possibilities. But i'm worried that I might have missed something. Let me know if you have any ideas! TIA! 3. Fuel Pump The fuel pump in 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. It is easy to find a spare in a wrecking shop or parts store. It is easy to test them: simply put your DMM into resistance mode and measure 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 have an ECU that needs to know the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown. A malfunctioning G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, or a misfire while in the gear. It is possible that your sensor is failing and requires to be replaced if you encounter any of these signs. The good thing is that they are quite affordable and easy to find, especially if you're looking at a Bosch model, which is what we have. Alternately, GM's version this part would be a good option. 5. Tachometer A malfunctioning engine speed sensor could be the cause of a slew of problems in your vehicle. This Resource site is an important part of the transmission in your Audi since it sends information to the ECU on how fast or slowly the car's engine is turning. This sensor could cause the transmission to fail and other components of the car to be affected. The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig, and boost and then transmitting it to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, 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. You should see the resistance to be around 1000 ohms between these points. This part is common across the Audi 80-100-200-RS2 model, ranging 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.