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 on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer in the instrument cluster. 1. Engine Speed Sensor The grey wire is located on the outside of the transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer in instrument cluster. The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start 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, possibly indicating chain stretch or a jumped link on 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 can be a bit difficult to test since there are various pins on the connector and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should read about 1000 ohms. If you're having issues with this component, look for evidence of coolant or oil in the connector bay. 2. https://bennett-ashley.federatedjournals.com/10-healthy-habits-for-a-healthy-audi-battery-key-replacement , when i was accelerating to the fullest speed from highway paytoll, i experienced massive power loss as if the engine was running out of gas or the injectors aren't firing at all. This morning i pull out the spark plugs, three were drenched in gazoline, the fourth was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stay closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. https://jsfiddle.net/cementcoat03/8npsvb1r/ got 0ohm. Therefore, i think the issue is somewhere else. I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine. I'm not certain what to do, as i believe that i've completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has suggestions, please share them! TIA! 3. Fuel Pump The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical 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 simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms. 4. ECU The ECU of our 20vt turbo (3B AAN ABY) engines needs to be aware of the speed and position of the crankshaft to determine fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes on the diagnostic scanner which can lead to engine shutdown. The signs of a failing G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when you are in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these signs. They're inexpensive and easy to locate particularly when they're a Bosch model like ours. Alternately, GM's version this component is an excellent choice. 5. Tachometer A failing engine speed sensor could be the cause of a slew of problems in your vehicle. It's an essential component of the transmission in your Audi, as it transmits information to the ECU on how fast or slowly the engine is spinning. If this sensor fails, it can affect the performance of the transmission, as well as the other car's components. The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU utilizes this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the 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 pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This part is common 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, so you might find good ones in wrecking yards.