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How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission over the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer in 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 where the camshaft is located so that it can start spark and injectors in the right way.

If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test because there are several connector pins, and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully functional, it should read approximately 1000 ohms. Check for signs of coolant or oil in the connector bay if you have issues with this part.

2. audi key replacement near me , while accelerating at full speed from the highway paytoll i had an abrupt drop in power like the engine is out of gas or the injectors aren't firing at all. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the 4th one was dry. I placed a tissue over each injector hole and when i start the engine without sparks, the 3 with gazoline jump out. The 4th one remains shut. I tried to test the ground connections 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 PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of that is -49c even after unplugging it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily 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 on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know the position and speed 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 are experiencing issues with either of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.

A damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, and/or a misfire while in gear. If you are experiencing any of these issues, it is likely that your sensor is failing and requires replacement. They're inexpensive and easy to locate, especially when they're a Bosch sensor like ours. If you prefer, GM's version of this component is a good option.

5. Tachometer


A damaged engine sensor could cause a variety of issues in your vehicle. It's a vital component of your Audi's transmission, since it relays information to the ECU about how fast or slow the car's crankshaft is turning. This sensor can cause the transmission to fail and other components in the car to be affected.

The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. Also, you can check 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 see an average resistance of 1000 ohms between these two points. This is a standard part across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.

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