How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer 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 alert to the G5 Tachometer in instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC and also where the camshaft lies to trigger the spark and injectors.
If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky as there are two different connector pins and they serve different purposes but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth one was dry. When i crank the engine, there are no sparks i put tissue on the top of each of the injector holes and the 3 that were drenched in gazoline pop out, but the 4th one stays closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero Ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID but with no luck. audi keys replacement is able to start when the G28 is unplugged and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.
I'm not sure what to do, i believe that i've completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has 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 similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to know the position and speed of the crankshaft to make decisions about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.
A damaged G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. If you are experiencing any of these issues, it is likely that your sensor is failing and needs replacing. They're cheap and easy to find, especially in the case of a Bosch model like ours. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A failing engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission of your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is turning. If the sensor fails, it can cause problems for the transmission and the other car's components.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It transmits a signal via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, as well as timig. audi key programming near me relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms between these two points. This is a typical part across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.