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 at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) and then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, just above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor serves as a reference to correlate 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 in the right way.

If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging because there are two connector pins, and they perform different functions but the best method to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or my injectors were not 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, there are no sparks i put tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th one stays shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. So i assume the problem is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue continues to occur 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 while the actual pressure is 0.

I'm not certain what to do, as i think i've pretty much ruled out everything else. I'm worried that i might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is easy to test them - just switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that has to know the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, for example. It audi lost key uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either one of these, the diagnostic scanner will display codes that could cause the engine shutting down.

The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal, and/or a misfire when you're in gear. If you experience any of these problems, it is most likely that your sensor is deteriorating and should be replaced. The good thing is that more info they are very affordable and readily available particularly in the case of the Bosch model, like ours. Alternately, the GM version of this component is also a good choice.

5. Tachometer

A faulty engine speed sensor could be get more info the reason behind numerous problems in your vehicle. It's an essential component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slow the car's engine is turning. This sensor can cause the transmission to fail and other components of the car to be affected.

The G5 engine audi spare key replacement sensor is located near the edge of the transmission, just above the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. 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 read more cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. There should be the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.