How to Replace an audi spare key cost G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer in 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 a signal to ECU pin T55/49 through the grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC, and the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate chain stretch or a jumped link on the upper timing chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test as there are several connector pins, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when it is in full operation. If you are having problems with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a massive reduction in power. It was like the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs. Three were drenched with gazoline the fourth one was dry. I placed a tissue over each hole in the injector and when I turn the engine on without sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming the issue is in another place.

I also tried to reset the PID without success. The car can start when the G28 is disconnected 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 temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.

I'm not sure what to do. I feel like i've pretty much ruled everything else out. But i am afraid i might have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or in a local parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from 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 needs to know the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

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 possible that your sensor is failing and needs to be replaced if you experience any of these signs. The good thing is that they are quite affordable and easily accessible, especially when you're looking at an Bosch model, like ours. Alternately, GM's version this part is a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your vehicle. It is a crucial part of the audi replacement keys's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, as well as timig. It also relays 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, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This is a standard part across the key audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.