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How to Replace an replacement audi a3 key G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated near the edges of the transmission above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect 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 activate 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. The code won't appear without the additional information supplied by other sensors (G4 or G40).

It's a bit tricky to test as there are several connector pins, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading around 1000 ohms. Examine for signs of coolant, or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant decrease in power. It was as if the engine was running out of gas. Or, my injectors were not firing. I took out the spark plugs this morning, three 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 hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th stay closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. I think the issue is in another location.

I also tried to reset the PID without success. The car is able to start when the G28 is disconnected and it runs perfectly when it is plugged in however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, but i believe that i've ruled out everything else. However, i'm afraid that I might have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style sensor is the same as 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 from a parts store. It is simple to test them: simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner which can cause the engine to shut down.

Some of the symptoms of a failing G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when in gear. If you experience any of these issues it is most likely that your sensor is deteriorating and needs replacing. The good news is that they are very cheap and easily accessible, especially in the case of a Bosch sensor, which is what ours are. If you prefer, GM's version of this component is an option.

5. Tachometer

A faulty engine speed sensor could be the cause of numerous issues with your vehicle. It is an important part of the transmission in your replacement audi a3 key, as it transmits information to the ECU regarding how fast or slowly the car's engine is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, 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 in these areas. This part is common across the audi tt key replacement 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find some good ones in wrecking yards.