How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located on the outside of the transmission, above the flywheel gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of the upper chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).

It can be a bit difficult to test because there are different pins on the connector, 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 about 1000 ohms when it is operating at its maximum. Look for signs of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss as if the engine was running out of gas or injectors aren't firing any more. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. When i crank the engine without sparks i put tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stay shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I'm assuming the issue is in another place.

I also tried to reset PID without success. The car will start if the G28 is unplugged and it runs perfectly when it is connected, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine.

I don't know what to do. I think I've eliminated everything else. However, i'm afraid that I may have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sensor is identical to the G4 and they both work in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or at a parts store. It is read more simple to test them - simply put your DMM into resistance mode and test 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 are equipped with an ECU that needs to know the position and speed of the crankshaft to make decisions about fuel injector timing etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a check here problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.

A damaged G28 sensor could cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, or a misfire while in the gear. If you have any of these problems, it is most likely that your sensor is going bad and requires replacement. The good thing is check here that they are very cheap and easily accessible particularly if you're looking at an Bosch model, which is what ours are. Alternatively, the GM version of this part is also a great option.

5. Tachometer

A malfunctioning read more engine speed sensor could be a cause for many issues in your vehicle. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it could affect the performance of the transmission, as more info well as the other car's components.

The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then processes the signal to control fuel, timig, and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. This is a standard part across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.