How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission 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 located on the edge of transmission, just above the flywheel ring. This 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 indicator to the G5 Tachometer in instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors in the right way.
If this sensor fails to function, 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 indicate a chain stretch or a jump in the chain link of the upper chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test because there are several pins on the connector and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is at full operation. Check for evidence of coolant or oil in the connector bay if there are issues with this component.
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 the injectors are not firing at all. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was unclean. I placed a tissue over each injector hole, and when i start the engine with no sparks, the 3 with gazoline jump right out. The 4th one stays shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. I assume that the problem is in another location.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do. I feel like i've pretty much eliminated everything else. But i'm worried that i might have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that needs to know the position and speed of the crankshaft to make decisions about fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes on the diagnostic scanner which could cause engine shut down.
A failing G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, and/or a misfire in gear. If you are experiencing get more info any of these issues it is most likely that your sensor is going bad and should be replaced. They are cheap and easy-to-find particularly when they're an Bosch model like ours. If you prefer, GM's version of this component is an option.
5. Tachometer
A failing engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. If the sensor fails, it will affect the performance of the transmission as well as the rest of the car's components.
The G5 engine speed sensor website is located at the outside of the transmission, above the flywheel ring gear and sends a read more signal directly to the ECU at pin T55/49 through a grey wire. The ECU uses this signal to regulate fuel and boost, and also timig. It also transmits it to the G5 Tachometer located in the instrument lost audi keys cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 replacement key for audi a4 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This is a standard part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.