Notes

Your Worst Nightmare Concerning Audi G28 Bring To Life
How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge just above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer 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 a signal to ECU pin T55/49 using an uncolored wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

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

If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).

It is a little tricky to test since there are several pins on the connector, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is at full operation. Examine for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had a big cut in power as if the engine was running out of gas or injectors are not firing any more. This morning i pull out the spark plugs, 3 were soaked with gazoline and the fourth one was dry. I put tissue over each injector hole, and when i turn the engine on without sparks, the 3 with gazoline jump right out. The fourth one remains shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I'm assuming the issue is elsewhere.

spare audi key G28CarKeys tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c, even if I unplug it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if 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 afraid i may have missed something. If anyone has suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is simple to test them - just put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. To do this, it makes use of 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 codes that could cause an engine shutdown.

A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or an unfire when in gear. It is probable that your sensor is failing and requires to be replaced if you encounter any of these signs. They're inexpensive and easy to locate especially if they're an Bosch model like ours. Alternately, the GM version of this unit is also a great option.

5. Tachometer

A damaged engine sensor could cause a variety of issues within your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor could cause the transmission to malfunction and other components of the car to be affected.


The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and processes this signal to control fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the 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. You should observe approximately 1000 ohms of resistance between those two pins. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find some good ones in wrecking yards.

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