How to Replace an replacement key audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, 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 signals through the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the 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 show the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing can be a bit difficult since there are two pins for the connector audi Q7 Replacement Key and they have different functions but the best way to test it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is operating at its maximum. If you're having issues with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed, i noticed a huge decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs. Three were drenched in gazoline, the fourth was dry. When i crank the engine with no sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th stays closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. I think the issue is elsewhere.

I also tried to reset the PID but without success. The car is able to start when the G28 is unplugged and it runs perfectly when it is plugged in however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.

I'm not sure what to do, i feel i have pretty much completely ruled out all other possibilities. But i am afraid i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives 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. You can easily locate a spare in a wrecking shop or a parts store. It is easy to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing up). 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 speed and position of the crankshaft in order to make a decision about 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 encounter a problem with either one of these, the diagnostic scanner will display codes that could cause an engine shutdown.

A failing G28 sensor could result in an inaccurate speed counter for your gearbox or a gearbox that shifts more quickly than normal, and/or a misfire while in gear. If you experience any of these issues it is likely that your sensor is failing and should be replaced. The good news is they are very affordable and easily accessible, especially in the case of the Bosch model, which is what we have. Alternatively, the GM version of this unit is also a good option.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for a slew of problems in your car. It is an important part of the transmission in your audi etron key since it sends information to the ECU regarding how fast or slowly the car's engine is turning. 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 sends an electrical signal through 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 test for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can verify 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 detect a resistance of approximately 1000 ohms in these areas. This is a common part that is found across the Audi Q7 Replacement Key 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.