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. The sensor is located near the transmission's edge over the flywheel gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has 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, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jump in the chain link of the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky as there are two different connector pins, and they perform different functions however the best way to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. If you're having issues with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power like the engine is running out of gas or injectors are not firing any more. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the fourth was unclean. When I crank the engine, there are no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is somewhere else.
I also tried to reset the PID without success. The car can start when the G28 is unplugged and is running fine when it is plugged in however it has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not here plugged in, shows temperatures of -49c. I also noticed that the oil gauge in the check here cockpit shows 2 bar but the actual pressure is 0.
I'm not sure what to do, i feel i have pretty much eliminated everything else. I'm afraid i may have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the more info 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is easy to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They must get more info be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must know the speed and position of the crankshaft in order to make a decision 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 goes wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.
Some of the signs of a failed G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker website than normal and/or a misfire when you are in gear. It is likely that your sensor is failing and needs to be replaced if you encounter any of these symptoms. The good thing is that they are very cheap and readily available, especially in the case of an Bosch unit like ours. Alternatively, GM's version of this part is an excellent choice.
5. Tachometer
A failing engine speed sensor could be a cause for many issues in your car. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU about how fast or slowly the engine is spinning. If this sensor fails, it could disrupt the performance of the transmission and the rest of the car's components.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU is then able to process the signal to control 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. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is a common part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.