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How to Replace an Audi G28 Engine Speed Sensor In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster. 1. Engine Speed Sensor The sensor is located at the edge of the transmission, 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 flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer in instrument cluster. The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors in the right way. If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40). It is a little tricky to test as there are different pins on the connector and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is at full operation. Examine for evidence of coolant or oil in the connector bay if you are experiencing issues with this part. 2. Injectors Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I put tissue over each injector hole, and when i start the engine without sparks, the 3 with gazoline jump right out. The 4th one remains closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. I think the issue is somewhere else. I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine. I'm not sure what to do. I think I've ruled everything else out. I'm worried that i might have missed something. Let me know if you have any ideas! TIA! 3. Fuel Pump The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from 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 end facing upwards). They must be infinite Ohms. 4. ECU Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft in order to make decisions about fuel injector timing etc. To accomplish this, it utilizes 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 that can cause the engine to shut down. Some of the symptoms of a failing G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when you're in gear. It is likely that your sensor is failing and requires to be replaced if you notice any of these symptoms. The good news is they are quite affordable and easily accessible particularly in the case of the Bosch unit like ours. Alternatively, the GM version of this component is also a good choice. 5. Tachometer A damaged engine sensor could cause a variety of issues in your car. It's an essential component of the transmission of your Audi because it relays information to the ECU regarding how fast or slowly the engine is spinning. If this sensor fails, it can cause problems for the transmission and the rest of the car's components. The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then processes the signal to control the flow of fuel, timig and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. The Keylab should observe around 1000 ohms of resistance between these two points. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find them in wrecking yards.