How to Replace an replacement key audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located on the edge of the transmission, above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals 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 signals to the G5 Tachometer located in the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.

If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain stretching 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 since there are two connector pins and they perform different functions however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is in full operation. If you're experiencing issues with this part, check for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed I noticed a significant drop in power. It was as if the engine was running 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 start the engine with no sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th one stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I assume that the problem is somewhere else.

I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62) even if it is not plugged in, 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 certain what to do, as i feel i have pretty much ruled out everything else. I'm worried that i might have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and measure the resistance 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 must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

A failing G28 sensor could result in an inaccurate gearbox speed counter or a gearbox that shifts more quickly than normal, and/or a misfire while in gear. It is possible that the sensor is failing and needs to be replaced if you experience any of these signs. The good news is that they are very cheap and easy to find particularly in the case of a Bosch sensor, which is what we have. Alternatively, the GM version of this component is also a great option.

5. Tachometer

A faulty engine speed sensor could be the cause of many issues in your vehicle. It's an essential component of the transmission of your key audi since it sends information to the ECU about how fast or slow the engine is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits signals via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to control the flow of fuel and boost as well as timig. It also transmits it to the G5 Tachometer located in 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 on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is a common part across the audi key fob replacement cost 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.