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How to Replace an Audi G28 Engine Speed Sensor In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge, above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster. 1. Engine Speed Sensor The grey wire is situated on the outside of the transmission, above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster. The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the position of the camshaft, in order to activate the spark and injectors. If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain is stretched or a jump link on the upper chain of timing. However the code will not appear on its own, without additional information from other sensors (G4 and G40). It's a bit tricky to test as there are different pins on the connector and each one has different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should be reading approximately 1000 ohms. If you're having issues with this sensor, look for evidence of oil or coolant in the connector bay. 2. Injectors Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power 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 soaked with gazoline and the 4th 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 right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I'm assuming that the issue is somewhere else. I also tried to reset PID without success. The car is able to start if the G28 is disconnected and it runs perfectly when it is connected however it is experiencing intermittent misfires 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 when the actual pressure is 0.0 when i rev the engine. I'm not sure what to do, but i feel i have pretty much completely ruled out all other possibilities. However, i'm afraid that I might have missed something. Let me know If you have any suggestions! TIA! 3. Fuel Pump The fuel pump in the g28 receives 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 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 between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms. 4. ECU Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these, the diagnostic scanner will show the codes that could trigger the engine shutting down. The signs of a failed G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or misfiring when in gear. It is likely that the sensor is failing and needs to be replaced if you encounter any of these symptoms. They're inexpensive and easy to locate particularly if they're an Bosch sensor like ours. Alternately, GM's version this part would be an excellent choice. 5. g28carkeys could be the cause of many problems in your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is spinning. This sensor can cause the transmission to malfunction and other car components to be affected. The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU uses this signal to control the flow of fuel and boost and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a common part across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.