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 at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through the grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumped chain link in the upper chain. The code won't show without the additional information provided by other sensors (G4 or G40).
It is a little tricky to test since there are different connector pins, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is in full operation. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine had run out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth one was dry. When I crank the engine without sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stay closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. Therefore, i think the issue is somewhere else.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. how much is an audi key replacement noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do. I feel like i've pretty much ruled everything else out. 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 is activated by a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80, 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or at a parts store. It is easy to test them: simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing up). They should be infinite ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft in order to make decisions about timing of the fuel injector, for example. 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.
Some of the symptoms of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when in gear. It is probable that the sensor is failing and requires to be replaced if you experience any of these symptoms. They're cheap and easy to find especially in the case of a Bosch sensor like ours. Alternatively, GM's version of this component is a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind a slew of issues in your vehicle. It's an essential component of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components in the car to be affected.
how much is a replacement audi key is located at the outside of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via a grey wire. The ECU is then able to process this signal to control fuel, timig, and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. You can also 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 see around 1000 ohms of resistance between those points. This is a common component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.