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How to Replace an audi tt key case G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.

If this sensor fails to function, the ECU will display an error code P00160. This means 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 jumpy chain link in the upper timing chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit tricky since there are two connector pins, and they have different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. Check for signs of coolant, or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday accelerating full speed from highway paytoll i had a big cut in power as if the engine was running out of gas or the injectors are not firing at all. I took out the spark plugs this morning, three were drenched in gasoline and the 4th was dry. I put tissue over each hole in the injector and when I turn the engine on without sparks, the three with gazoline jump right out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is in another place.

I also tried to reset the PID but without success. The car is able to start when the G28 is unplugged and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when it is unplugged, 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 certain what to do, i feel i have pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and repair RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is easy to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing up). They should be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.

The signs of a failed G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when you're in gear. It is probable that your sensor is failing and needs to be replaced if you encounter any of these symptoms. They're cheap and easy to find particularly if they're an Bosch model like ours. Alternatively, GM's version of this component is an excellent choice.

5. Tachometer

A malfunctioning engine speed sensor could be the reason behind numerous issues with your car. It's a vital component of your audi keys's transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to fail and other components of the audi a1 car key to be affected.

The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to control the flow of fuel and boost and also timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between these two points. This part is common across the audi tt key fob not working 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.