Why No One Cares About Audi G28

How to Replace an Audi Key Replacement G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located at the edge of transmission over the flywheel 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

It is located on the outside of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference to correlate 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 trigger spark and injectors according to the situation.

If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

It is a little tricky to test since there are different connector pins, and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is fully functional, it should read approximately 1000 ohms. Examine 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 massive power loss like the engine is running out of gas or injectors are not firing any more. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth one was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stay closed. I checked 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 the PID without success. The car will start when the G28 is unplugged and runs fine when it is connected however it has intermittent misfire issues at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I believe that I've eliminated everything else. However, i'm afraid that I might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or at a parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines needs to know the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. To do this, it utilizes 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 show the codes that could trigger an engine shutdown.

A failing G28 sensor Audi key replacement can cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, or an unfire when in gear. It is probable that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good thing is that they are very cheap and readily available particularly in the case of a Bosch model, which is what ours are. Alternately, the GM version of this component is also a good choice.

5. Tachometer

A damaged engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the transmission of your Audi, as it transmits information to the ECU regarding how fast or slow the engine of the car is spinning. This sensor can cause the transmission to fail and other components in the car to be affected.

The G5 engine speed sensor is located on the edge of the transmission just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU then uses and Audi Key Replacement processes this signal to control fuel, timig and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Also, 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 and pin T26a/12. There should be the resistance to be around 1000 ohms between these two points. This is a typical part that is found across the audi connect key 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.