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How to Replace an audi tt key 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 edge of transmission just above the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49) and audi keyless entry then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped 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).

It can be a bit difficult to test because there are several pins on the connector and each has its own 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 it is at full operation. If you're having issues with this component, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the 4th one was dry. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the ones that have gazoline pop right out. The 4th one stays closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. Therefore, i think the issue is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.

I don't know what to do. I believe that I've all other possibilities out. But i am afraid I may have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sender 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. Testing them is easy by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner which can lead to engine shutdown.

Some of the symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when you're in gear. If you have any of these issues, it is likely your sensor is deteriorating and requires replacement audi car key audi a3 key (Resource). The good thing is that they are quite affordable and easily accessible, especially in the case of a Bosch sensor, which is what ours are. Alternatively, GM's version of this part is a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your car. It is an important part of the transmission in your audi key programmer because it relays information to the ECU on how fast or slow the car's engine is turning. This sensor could cause the transmission to fail and other components in the car to be affected.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU then processes the signal to control fuel, timig, and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those points. This is a standard part across the audi advanced key 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.