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How to Replace an Audi G28 Engine Speed SensorIn this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.1. Engine Speed SensorIt is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU uses this information to control the amount of fuel and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.The sensor is used to link the G40 Camshaft position Sensor. replacement audi a3 key must know when the crankshaft reached TDC, and the position of the camshaft, in order to activate the spark and injectors.If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won’t appear without the additional information provided by other sensors (G4 or G40).It can be a bit difficult to test as there are several pins on the connector, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is operating at its maximum. If you are having problems with this sensor, look for evidence of coolant or oil in the connector bay.2. InjectorsYesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was like the engine had run out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, three were drenched with gazoline the fourth one was dry. I put a piece of tissue over each injector hole and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one stays closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero Ohm. I’m assuming the issue is somewhere else.I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However, the intermittent misfire problem persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.I don’t know what to do. I think I’ve ruled everything else out. I’m concerned that i may have missed something. If anyone has any ideas please chime in! TIA!3. Fuel PumpThe fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or in a local parts store. It is simple to test them – put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector’s side up) and 2 (2nd from the left on the black end of the connector). They must be infinite ohms.4. ECUOur 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the position and speed of the crankshaft to make decisions about timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either one of these, the diagnostic scanner will display codes that could cause an engine shutdown.A malfunctioning G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or an unfire when in gear. If you have any of these issues, it is likely that your sensor is failing and should be replaced. The good news is they are very cheap and readily available particularly if you’re looking at a Bosch model, which is what we have. You can also choose the GM version of this unit is also a great option.5. TachometerA malfunctioning engine sensor can cause a myriad of issues within your vehicle. It is an important part of the transmission in your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is turning. This sensor can cause the transmission to fail and other components in the car to be affected.The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these points. This is a typical component across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.