How to Replace an Audi G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is situated near the edges of the transmission above the flywheel ring gear. It transmits a signal the ECU via the grey wire (T55/49), then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using an uncolored wire. The ECU utilizes this information to regulate fuel and boost. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).

It can be a bit difficult to test since there are different pins on the connector, 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 around 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge reduction in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were drenched in gasoline and the 4th was dry. When i crank the engine, there are no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.

I also tried to reset the PID but without success. The car is able to start if the G28 is unplugged and runs fine when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.

I'm not sure what to do. I think I've eliminated everything else. But i am afraid I might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal 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 so you can easily find one at a salvage yard or from a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). 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 to make decisions regarding fuel injector timing etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will display the codes that could trigger an engine shut down.

A failing G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you experience any of these problems, it is likely that your sensor is going bad and requires replacement audi key fob. They're inexpensive and easy to locate particularly in the case of a Bosch sensor like ours. If you prefer, GM's version of this part is an excellent choice.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your vehicle. It's a vital component of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. This sensor can cause the transmission to fail and other components of the car to be affected.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can check for sensor failure by examining the continuity of 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 [79]), and between pin T6a/1 and replacement audi Key fob pin T26a/12. You should detect an average resistance of 1000 ohms between these points. This is a typical part across the audi keyless entry 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.