How to Replace an audi Car Key cover G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the edge of transmission just above the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC, and where the camshaft lies to trigger the spark and injectors.

If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper chain. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging because there are two pins for the connector and they serve different purposes but the most effective method of testing it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is operating at its maximum. Check for signs of coolant or oil in the connector audi a3 key fob, pukkabookmarks.com, bay if there are issues with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant decrease in power. It was as if the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, 3 were drenched with 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 3 with gazoline jump out. The fourth one remains closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. I think the issue is somewhere else.

I also tried to reset the PID but without success. The car is able to start when the G28 is unplugged and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when it is unplugged, shows an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do, but i feel i have pretty much ruled out everything else. I'm worried that i might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. It is simple to test them - simply put 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 have an ECU that must know the position and speed of the crankshaft to make decisions regarding fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that could cause engine shut down.

A failing G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire in the gear. It is possible that your sensor is failing and requires to be replaced if you experience any of these signs. They are cheap and easy-to-find, especially if they're a Bosch unit like ours. Alternately, GM's version this part would be an option.

5. Tachometer

A faulty engine speed sensor could be the reason behind numerous issues with your car. It is a crucial part of the audi key fobs's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. If this sensor fails, it can disrupt the performance of the transmission as well as the rest of the car's components.

The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU then processes this signal to regulate the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms in these areas. This part is common across the replacement audi a3 key 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU So, you may find some good ones in wrecking yards.