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What Are The Reasons You Should Be Focusing On Enhancing Audi G28
How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located near the edges of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49), then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, above the flywheel ring. This 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 a signal to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumpy chain link in the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).

It can be a bit difficult to test as there are various pins on the connector and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.

2. Injectors


Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs, three were soaked with gazoline and the fourth one was dry. When I start the engine, there are no sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stay shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I think the issue is in another location.

I also tried to reset PID without success. The car will start when the G28 is unplugged and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.

I'm not sure what to do. audi key fob feel like i've pretty much all other possibilities out. But i am afraid i might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from 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. It is easy to find an extra in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines must know both the position and speed of the crankshaft to determine fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either one of these, the diagnostic scanner will display codes that could cause an engine shutdown.

The signs of a failing G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. If you have any of these issues it is most likely that your sensor is going bad and needs replacing. They are cheap and easy-to-find especially in the case of an Bosch unit like ours. Alternatively, the GM version of this part is also a good choice.

5. Tachometer

A failing engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission in your Audi since it sends information to the ECU regarding how fast or slow the car's engine is spinning. If this sensor fails, it will disrupt the performance of the transmission and the other car's components.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU then processes the signal to control fuel, timig, and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should observe approximately 1000 ohms resistance between those two pins. This is a standard part across the Audi 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.