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

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge over the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49), then to the tachometer located in 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 then uses this information to control fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.

If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging since there are two pins for the connector and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when it is operating at its maximum. If you're experiencing issues with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs. Three were drenched in gazoline, the fourth was dry. When i crank the engine, there are no sparks, I put a piece of tissue on top of each injector hole and the 3 that were drenched in gazoline jump out but the 4th stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. I think the issue is somewhere else.

I also tried to reset the PID without success. The car is able to start if the G28 is disconnected and runs fine when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I'm not sure what to do. I believe that I've eliminated everything else. But i am afraid i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. Test them out to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's side). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines must know both the position and speed the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either one of these, the diagnostic scanner will show codes that could cause the engine shutting down.

A failing G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or an unfire when in the gear. If you are experiencing any of these problems, it is likely your sensor is deteriorating and needs replacing. The good news is that they are quite affordable and easy to find particularly in the case of an Bosch model, like ours. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous problems in your vehicle. It is a crucial part of your replacement audi key blade audi lost key fob (her latest blog)'s transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor could cause the transmission to fail and other components of the car to be affected.

The G5 engine speed sensor is situated on the outside of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then uses and processes the signal to control fuel, timig, and boost and then 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. Also, 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 as well as pin T26a/12. It should show approximately 1000 ohms resistance between these two points. This is the same across the audi a4 replacement key 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find them in wrecking yards.