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How to Replace an audi a4 key replacement G28 Engine Speed Sensor

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

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, just above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.

If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or 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 is a little tricky to test since there are various pins on the connector, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should read approximately 1000 ohms. Examine for signs of coolant or oil in the connector bay if you have 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 aren't firing at all. I pulled out the spark plugs this morning, 3 were soaked in gasoline, audi Keys and the fourth was dry. I put tissue over each injector hole, and when i turn the engine on without sparks, the three with gazoline jump right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming that the issue is elsewhere.

I also tried to reset PID but without success. The car can start if the G28 is unplugged and runs fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, i believe that i've eliminated everything else. But i'm worried that I might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or 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's side up) and 2 (2nd from the left on the black end of the connector). They should 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 in order to make decisions regarding timing of the fuel injectors, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.

A malfunctioning G28 sensor can cause an inaccurate speed counter for audi Keyless go the gearbox or a gearbox that shifts more quickly than normal, and/or a misfire in the gear. It is possible that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is that they are very affordable and easy to find particularly when you're looking at an Bosch model, like ours. If you prefer, GM's version of this part would be an option.

5. Tachometer

A faulty engine speed sensor could be a cause for many issues in your vehicle. It is an important part of the transmission in your audi tt key fob not working since it sends information to the ECU regarding how fast or slow the car's engine is turning. If this sensor fails, it can cause problems for the transmission, as well as the other car's components.

The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 via an uncolored wire. The ECU uses this signal to control fuel and boost, and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is the same across the audi smart key replacement 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU So, you may find them in wrecking yards.