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One Of The Most Innovative Things Happening With Audi G28
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 at the edge of transmission, above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to regulate fuel and boost. audi key programming thekeylab.co.uk sends an alert 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 has to be aware of when the crankshaft has reached TDC and also the position of the camshaft, in order to activate the spark and injectors.

If this sensor fails, the ECU will display an error code P00160. 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 jump in the chain link of the upper chain. The code won't appear without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test as there are different connector pins, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is at full operation. Look for evidence of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or the injectors are not firing at all. In the morning, i removed the spark plugs, three were drenched with gazoline the fourth was dry. I put tissue over each hole in the injector and when i turn the engine on without sparks, the ones that have gazoline pop right out. The 4th one remains shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero Ohm. Therefore, i think the issue is in another place.

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

I'm not sure what to do. I think I've eliminated everything else. But i am afraid i might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or a parts store. It is easy to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to be aware of the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could cause the engine shutting down.

Some of the symptoms of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when in gear. If you experience any of these issues, it is most likely that your sensor is failing and should be replaced. The good thing is that they are very affordable and readily available particularly in the case of an Bosch sensor, which is what we have. You can also choose the GM version of this component is also a great option.

5. Tachometer

A failing engine sensor could cause a number of problems within your vehicle. It's an essential component of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is spinning. If this sensor fails, it can affect the performance of the transmission and the other car's components.

The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU then uses and processes this signal to control fuel, timig and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This is a typical part that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.