Audi G28: The Good, The Bad, And The Ugly
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. This sensor is situated at the edge of transmission, above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through the grey wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors in the right way.
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 a chain stretch or a jump in the chain link of the upper chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test as there are several connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. If you are having problems with this sensor, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced massive power loss like the engine is out of gas or the injectors are not firing at all. I took out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. I put tissue over each injector hole and when I turn the engine on without sparks, the ones that have gazoline pop right out. The 4th one stays closed. I inspected 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 with no success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However the intermittent misfire issue persists 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 bar while the actual pressure is zero.
I'm not sure what to do. I feel like i've pretty much ruled everything else out. However, i'm afraid that I might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical 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 - 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 connector's side). They should 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 to make decisions regarding timing of the fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these, the diagnostic scanner will show codes that could cause an engine shutdown.
The signs of a failed G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when you're in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these symptoms. They're cheap and easy to find, especially if they're a Bosch sensor like ours. Alternatively, the GM version of this component is also a great option.
5. Tachometer
A failing engine sensor could cause a number of problems in your car. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. If the sensor fails, it can affect the performance of the transmission and the rest of the car's components.
genuine audi key replacement is located near the edge of the transmission, just above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU is then able to process this signal to control fuel, timig, and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This is a typical part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.