How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through the grey wire. The ECU uses this information to control fuel and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC and also where the camshaft lies in order to activate the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain of timing. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky as there are two different pins for the connector and they serve different purposes however the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is operational, it should read around 1000 ohms. Look for signs of coolant or oil in the connector bay if there are issues with this part.

2. Injectors

Yesterday accelerating full speed from highway paytoll, I experienced massive power loss like the engine is running out of gas or injectors are not firing anymore. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was dry. When I start the engine with no sparks i put tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stay shut. I tested 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 in another location.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not certain what to do, i feel i have pretty much completely ruled out all other possibilities. But https://appealsponge68.werite.net/12-facts-about-audi-car-key-replacement-to-make-you-think-twice-about-the-cooler 'm worried that I may have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by 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 from a parts store. It is easy to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to know the speed and position of the crankshaft to make a decision about timing of the fuel injector, for example. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

The signs of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when you are in gear. It is likely that the sensor is failing and needs to be replaced if you encounter any of these symptoms. The good thing is that they are very cheap and readily available particularly when you're looking at an Bosch sensor, which is what ours are. Alternately, GM's version this part would be a good option.

5. Tachometer



A damaged engine sensor could cause a myriad of issues in your car. It is a crucial part of your Audi's transmission, because it communicates to the ECU about how the car's crankshaft is turning. This sensor can cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU then uses and processes the signal to control the flow of fuel, timig and boost, and also sends it on 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, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This is a common component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.