How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located on the edge of the transmission just above the flywheel ring gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating the chain is stretched or a jump link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky because there are two connector pins and they perform different functions but the best method to test it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is operating at its maximum. Check for signs of coolant, or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is running out of gas or injectors aren't firing any more. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was dry. When i crank the engine with no sparks, I put a piece of tissue on top of each injector hole and the 3 that were drenched in gazoline leap out, however the 4th one stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. Therefore, i think the issue is in another place.
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 audi q7 car key replacement occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. I'm afraid i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. Test them out by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft to make decisions about fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will show the codes that could trigger an engine shut down.
Some of the symptoms of a failed G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when you're in gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these signs. They're inexpensive and easy to locate, especially in the case of a Bosch model like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A failing engine speed sensor could be a cause for a slew of issues in your car. It's an essential component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor could cause the transmission to fail and other car components to be affected.
The G5 engine sensor 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 utilizes this signal to control the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find good ones in wrecking yards.