How to Replace an audi advanced key G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

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

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors accordingly.

If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of 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's a bit tricky to test because there are various connector pins, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is operating at its maximum. If you're having issues with this part, check for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced massive power loss as if the engine was running out of gas or the injectors are not firing any more. This morning i pull out the spark plugs. Three were drenched in gazoline, the fourth one was dry. I placed a tissue over each injector hole, and when i turn the engine on without sparks, the ones with gazoline jump right out. The fourth one remains closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.

I'm not sure what to do. I believe that I've ruled everything else out. But i am afraid I may have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or at a parts store. Testing them is easy - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make decisions regarding timing of the fuel injector, for example. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could lead to an engine shutdown.

Some of the symptoms of a failing G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal, and/or a misfire when you are in gear. If you have any of these problems, it is likely that your sensor is deteriorating and requires audi replacement keys. The good thing is that they are very affordable and readily available, especially if you're looking at an Bosch unit which is what ours are. You can also choose the GM version of this unit is also a good choice.

5. Tachometer

A damaged engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission in your Audi a3 spare key because it relays information to the ECU on how fast or slowly the car's engine is turning. If the sensor fails, it will affect the performance of the transmission, as well as the rest of the car's components.

The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to regulate the flow of fuel and boost as well as timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can test key for audi sensor failure by examining the continuity from the sensor to the tachometer. You can also 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. You should see a resistance of approximately 1000 ohms between these two points. This is a common feature across the audi a1 key 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU So, you may find them in wrecking yards.