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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 edge of transmission just above the flywheel gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer on 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 an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends a signal to the G5 tachometer 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 location of the camshaft in order to activate the spark and injectors. If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40). It is a little tricky to test because there are different connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when it is operating at its maximum. If you are having problems with this sensor, look for evidence of oil or coolant in the connector bay. 2. Injectors Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. I put tissue over each hole in the injector and when I turn the engine on without sparks, the 3 that have gazoline pop right out. The fourth one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. mouse click the following web page think the issue is somewhere else. I also tried to reset PID but without success. The car can start when the G28 is disconnected and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero. I'm not sure what to do, as i think i've pretty much ruled out everything else. But i am afraid I may have missed something. Let me know if you have any ideas! TIA! 3. Fuel Pump The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. It is simple 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 upwards). They should be infinite Ohms. 4. ECU Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner which can cause the engine to shut down. The signs of a failed G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when in gear. It is likely that your sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find particularly if they're a Bosch model like ours. If you prefer, GM's version of this part would be a good option. 5. Tachometer A failing engine speed sensor could be a cause for a slew of issues with your vehicle. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine is spinning. When this sensor fails, it could cause problems for the transmission and the other car's components. The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the amount of fuel and boost, as well as timig. It also relays it to the G5 Tachometer inside 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 check continuity between pin 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 approximately 1000 ohms of resistance between those points. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 Du So, you may find them in wrecking yards.