How to Replace an audi car key replacement G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace audi key fob the G28 engine speed sensor. The sensor is situated on the edge of the transmission above the flywheel ring gear. It sends a message 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 at the edges of the transmission, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors in the right way.

If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test because there are different 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. If the sensor is operational, it should read about 1000 ohms. Examine for signs of coolant or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the 4th was dry. When I crank the engine with no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th one stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero ohm. I assume that the problem is elsewhere.

I also tried to reset the PID without success. The car will start if the G28 is not plugged in and is running fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, programmed still shows temperatures of -49c. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.

I'm not certain what to do, but i feel i have pretty much ruled out everything else. 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 functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or parts store. It is simple to test them: simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and programmed speed of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will display codes that could cause the engine shutting down.

Some of the signs of a failed G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or a misfire when you are in gear. If you have any of these issues it is likely your sensor is failing and needs replacing. The good news is that they are very affordable and easily accessible particularly if you're looking at a Bosch sensor, which is what we have. Alternatively, the GM version of this component is also a good option.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues within your vehicle. It is an important part of the transmission in your Audi since it sends information to the ECU about how fast or slowly the engine of the car is turning. When this sensor fails, it will affect the performance of the transmission, as well as 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 an uncolored wire to the ECU pin T55/49. The ECU then processes this signal to control fuel, timig and boost and then sends it on to the G5 tachometer inside 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 [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms in these areas. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find some good ones in wrecking yards.