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One Of The Most Innovative Things That Are Happening With Audi G28
How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located at the top of the transmission above the flywheel ring gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via an uncolored wire. The ECU uses this information to regulate boost and fuel. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors in the right way.

If this sensor fails, the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing can be a bit difficult as there are two different pins for the connector and they perform different functions but the most effective way to test it is by measuring resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading about 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday accelerating full speed from highway paytoll i had a big cut in power like the engine is running out of gas or injectors are not firing any more. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. When I crank the engine, there are no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. I assume that the problem is in another location.

I also tried to reset the PID but with no luck. The car will start if the G28 is unplugged and it runs perfectly when it is plugged in but it still is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.

I'm not sure what to do. I believe that I've eliminated everything else. I'm worried that i might have missed something. If anyone has any ideas please chime in! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. Test them out to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's side). 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 to make a decision about fuel injector timing etc. To do audi a1 key replacement , it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will display codes that could cause an engine shut down.

A failing G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, and/or a misfire while in the gear. It is probable that the sensor is failing and needs to be replaced if you encounter any of these signs. The good thing is that they are quite affordable and easily accessible, especially if you're looking at a Bosch model, which is what we have. Alternatively, GM's version of this part would be an option.

5. Tachometer

A damaged engine sensor could cause a myriad of issues in your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slow the engine of the car is spinning. If this sensor fails, it will cause problems for the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to control the flow of fuel, timig and boost and then sends it on to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This is a typical component across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.