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

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is located on the outside of the transmission, above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer in 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 trigger spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing can be a bit difficult because there are two connector pins and they serve different purposes but the most effective way to test it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is in full operation. Look for signs of coolant, or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced an abrupt drop in power like the engine is running out of gas or the injectors are not firing anymore. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. I put a piece of tissue over each injector hole and when i start the engine without sparks, the 3 with gazoline jump right out. The 4th one stays closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero Ohm. I think the issue is elsewhere.

I also tried to reset PID but 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 issue still occurs at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, i think i've pretty much eliminated everything else. But i'm worried that I may have missed something. If anyone has any suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 receives 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 find a spare in a wrecking shop or 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 upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, for example. It uses a Crank Position Sensor Audi key copy G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.

The signs of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when in gear. If you have any of these problems, it is most likely that your sensor is going bad and needs replacing. The good thing is that they are very affordable and easily accessible particularly if you're looking at an Bosch sensor, like ours. Alternately, GM's version this part is an excellent choice.

5. Tachometer

A failing engine speed sensor could be a cause for numerous issues in your vehicle. It is a crucial part of your audi key Copy's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. When this sensor fails, it will disrupt the performance of the transmission, as well as the other car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to control fuel, timig and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. You can also check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a common component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.