How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows 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
It is located on the outside of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors accordingly.
If this sensor fails, the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain is stretched or a jump link on the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
how do i get a replacement key for my audi can be a bit difficult as there are two different connector pins, and they have different functions however the best way to test it is to measure resistance between the sensor and the ECU. If the sensor is functional, it should read around 1000 ohms. Check for signs of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant 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 drenched in gazoline, the fourth one was dry. When i crank the engine with no sparks, i place a tissue on the top of each hole in the injector and the 3 that were drenched in gazoline jump out but the 4th stay closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c even when i unplug it. how do i get a replacement key for my audi noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.
I don't know what to do. I feel like i've pretty much eliminated everything else. But i am afraid i might have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or parts store. Test them out - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end 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 needs to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these sensors, the diagnostic scanner will display codes that could cause an engine shutdown.
A malfunctioning G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire in gear. It is likely that your sensor is failing and requires to be replaced if you experience any of these symptoms. They're cheap and easy to find especially if they're a Bosch model like ours. If you prefer, GM's version of this part would be an excellent choice.
5. Tachometer
A damaged engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is spinning. If the sensor fails, it can affect the performance of the transmission and the rest of the car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost as well as timig. It also transmits it to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms in these areas. This is a common component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.