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How to Replace an audi a3 spare key G28 Engine Speed Sensor

Charles the Humble Technician shows you 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 sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside 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 the position of the camshaft, in order to activate the spark and injectors.

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

It is a little tricky to test as there are different pins on the connector and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is operational, it should read around 1000 ohms. Check for signs of coolant, or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is running out of gas or the injectors aren't firing any more. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When I crank the engine without sparks, i place a tissue on the top of each of the injector holes, the 3 drenched with gazoline jump out but the 4th stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I assume that the problem is elsewhere.

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

I don't know what to do. I believe that I've eliminated everything else. But i'm worried that I might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. It is easy to test them - just put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing up). They should 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 regarding timing of the fuel injector, for example. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.

The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when in gear. It is probable that the sensor is failing and needs to be replaced if you notice any of these signs. The good thing is that they are very affordable and easily accessible particularly when you're looking at an Bosch unit which is what we have. If you prefer, GM's version of this part is an excellent choice.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous problems in your car. It's an essential component of the transmission of your Audi key Shell since it sends information to the ECU about how fast or slowly the engine is spinning. If this sensor fails, it can cause problems for the transmission as well as the other car's components.

The G5 engine speed sensor audi Car key case is situated on the edge of the transmission, above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU utilizes this signal to regulate the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, 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. You should detect a resistance of approximately 1000 ohms between these points. This is a common part across the audi car key holder 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.