This Week's Top Stories Concerning 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 situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in 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 an electrical signal to ECU pin T55/49 through the grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends an indication to the G5 Tachometer in instrument cluster.

The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.

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


Testing can be a bit difficult as there are two different pins for the connector and they serve different purposes however the best method of testing it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms if the sensor is in full operation. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors are not firing any more. Today, i pulled out the spark plugs. new audi car key were drenched with gazoline the fourth was dry. When i crank the engine without sparks, i place a tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero Ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID but without success. The car can start if the G28 is unplugged and it runs perfectly when it is connected, but still has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I feel like i've pretty much eliminated everything else. But i am afraid i might have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is simple to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft to determine timing of fuel injectors, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.

Some of the signs of a failed G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or misfiring when you're in gear. If you are experiencing any of these issues, it is likely your sensor is failing and needs replacing. The good thing is that they are very affordable and easily accessible, especially if you're looking at a Bosch sensor, which is what ours are. Alternately, GM's version this component is an option.

5. Tachometer

A damaged engine sensor could cause a number of problems in your vehicle. It's an essential component of the transmission in your Audi since it sends information to the ECU about how fast or slowly the engine is spinning. If the sensor fails, it can cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes the signal to control the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, you can examine the continuity between pins 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. It should show approximately 1000 ohms resistance between these two points. This is the same across the Audi 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du You may also find some good ones in wrecking yards.