How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, just 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 within the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors.

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

It is a little tricky to test because there are various pins on the connector, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is fully operational, it should read around 1000 ohms. Check for signs of coolant or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge drop in power. It was as if the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs. Three were drenched in gazoline, the 4th one was dry. When I start the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th stays shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. So i assume the problem is in another place.

I also tried to reset PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c even when i unplug it. Also i noticed that the gauge for oil pressure 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. But i am afraid i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or parts store. Test them out to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's side). 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 to make a decision about timing of the fuel injectors, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.

The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when you're in gear. If you experience any of these issues, it is likely your sensor is failing and needs replacing. They're cheap and easy to find especially when they're a Bosch unit like ours. You can also choose the GM version of this component is also a good option.

5. Tachometer

A damaged engine sensor could cause a variety of issues within your vehicle. It's an essential component of your audi advanced key's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to fail and other car key cover audi components to be affected.

The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then processes the signal to control the flow of fuel, timig and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can check replacement key for audi sensor failure by examining the continuity of the sensor to the tachometer. Additionally, 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 observe around 1000 ohms of resistance between those points. This is the same across the audi New key 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find good ones in wrecking yards.