How to Replace an audi keyless go 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 just above the flywheel ring gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, just above the flywheel ring. The sensor sends signals through 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 instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit tricky because there are two pins for the connector and they have different functions but the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss like the engine is running out of gas or injectors are not firing anymore. I took out the spark plugs this morning, 3 were soaked with gasoline and the fourth was unclean. I put tissue over each injector hole, and when I start the engine with no sparks, the three with gazoline jump out. The 4th one stays closed. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I'm assuming that the issue is elsewhere.

I also tried to reset the PID with no success. The car is able to start if the G28 is disconnected and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.

I don't know what to do. I believe that I've ruled everything else out. But i'm worried that I might have missed something. If anyone has suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both are used 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. Testing them is easy to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to know the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes bad you will get codes on the diagnostic scanner that can cause the engine to shut down.

The signs of a failed G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when in gear. It is possible that your sensor is failing and needs to be replaced if you encounter any of these signs. They are cheap and easy-to-find, especially when they're a Bosch sensor like ours. Alternately, GM's version this part is a good option.

5. Tachometer

A failing engine speed sensor could be the cause of a slew of issues in your car. It is a crucial part of your audi advanced key a5 key fob [pratt-james-3.thoughtlanes.net]'s transmission, because it communicates to the ECU about how the car's crankshaft is rotating. If this sensor fails, it will 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, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then processes the signal to control the flow of fuel, timig and boost and then 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]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. This is a standard part across the audi q5 key 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.