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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. The sensor is located near the transmission's edge just above the flywheel gear. It sends a signal to the ECU via an uncolored wire (T55/49), then to the tachometer within the instrument cluster. 1. Engine Speed Sensor The sensor is located at 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 the grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 Tachometer within the instrument cluster. The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly. 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 is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40). It's a bit tricky to test because there are different connector pins, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should read approximately 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are problems with this part. 2. Injectors Yesterday accelerating full speed from highway paytoll i had a big cut in power like the engine is out of gas or injectors aren't firing any more. In the morning, i removed the spark plugs, 3 were drenched with gazoline the fourth one was dry. When I start the engine with no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stay closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero ohm. I assume that the problem is in another location. I also tried to reset the PID with no success. The car is able to start if the G28 is disconnected and it runs perfectly when it is connected however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero. I'm not sure what to do. I feel like i've pretty much all other possibilities out. But i am afraid I might have missed something. If anyone has any ideas please chime in! TIA! 3. Fuel Pump The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. audi tt keys G28 Car Keys is easy to find an extra in a wrecking shop or 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 at the connector's end facing up). They must be infinite Ohms. 4. ECU Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will display codes that could cause an engine shutdown. A failing G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you experience any of these problems, it is likely that your sensor is deteriorating and should be replaced. They're inexpensive and easy to locate particularly if they're an Bosch model like ours. Alternately, GM's version this part is an option. 5. Tachometer A malfunctioning engine speed sensor could be a cause for a slew of issues with your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU about how fast or slowly the engine is turning. If the 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 just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU then processes the signal to control fuel, timig and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms of resistance between these two points. This is a common component across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.