How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated near the edges of the transmission, above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49), then 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 sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are different connector pins, and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should read about 1000 ohms. If you are having problems with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a significant decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs. Three were drenched in gazoline, the fourth was dry. I placed a tissue over each injector hole, and when I turn the engine on without sparks, the three with gazoline jump out. The 4th one stays closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. I'm assuming the issue is somewhere else.
I also tried to reset the PID without success. The car is able to start when the G28 is not plugged in and it runs perfectly when it is plugged in but it still is experiencing intermittent misfires at higher RPM. replacement car key audi for coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not sure what to do, i believe that i've eliminated everything else. I'm worried that i might have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is simple 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 upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make decisions about timing of the fuel injectors, etc. In order to do this it makes use of 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 lead to engine shutdown.
A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or a misfire while in gear. If you have any of these problems, it is likely your sensor is failing and should be replaced. The good news is they are very cheap and easily accessible particularly if you're looking at the Bosch sensor, like ours. Alternately, the GM version of this component is also a good option.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU regarding how fast or slow the engine is turning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control the amount of fuel and boost, and also to timigrate. 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 to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms between these 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 the 1995 RS2 DU So, you may find them in wrecking yards.