How to Replace an audi a3 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 located at the top of the transmission just 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 situated on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also where the camshaft lies to trigger the spark and injectors.

If this sensor fails, the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit tricky as there are two different connector pins, and they perform different functions but the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is operational, it should read around 1000 ohms. Check for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a significant decrease 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 with no sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. Therefore, i think the issue is somewhere else.

I also tried to reset the PID but with no luck. The car can start if the G28 is unplugged and runs fine when it is plugged in however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.

I'm not sure what to do. I feel like i've pretty much all other possibilities out. But i am afraid I might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent by 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 locate the spare in a salvage shop or parts store. It is simple to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these, the diagnostic scanner will display codes that could cause an engine shut down.

Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you're in gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these symptoms. They're inexpensive and easy to locate especially if they're a Bosch unit like ours. Alternatively, the GM version of this component is also a good choice.

5. Tachometer

A failing engine speed sensor could be the cause of a slew of issues with your vehicle. It's an essential component of the transmission of your audi car key replacement cost a5 key fob [click to find out more], as it transmits information to the ECU on how fast or slow the engine is spinning. If the sensor fails, it can affect the performance of the transmission, as well as the other car's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also sends it to the G5 Tachometer in instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Additionally, you can verify 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 observe approximately 1000 ohms of resistance between those two pins. This part is common across the audi q7 replacement key 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 DU So, you may find them in wrecking yards.