How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated near the edges of the transmission above the flywheel ring gear. It transmits a signal the ECU via an uncolored wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

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

If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched 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).

It's a bit tricky to test since there are various pins on the connector, and each one has different functions. The best way to do it is to measure 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 sensor, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or, my injectors were not firing. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the ones with gazoline jump right out. The 4th one stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I assume that the problem is somewhere else.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However, the intermittent misfire here problem continues to occur 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 bars while the actual pressure is 0.

I'm not sure what to do, as i think i've pretty much audi car keys replacement eliminated everything else. But i am afraid I may have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. It is easy to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. In order to do this it uses 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 the codes that could trigger an engine shut down.

A malfunctioning G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or a misfire in gear. It is likely that your sensor is failing and needs to be replaced if you experience any website of these symptoms. The good news is they are very affordable and readily available particularly in the case of a Bosch unit which is what ours are. Alternately, GM's version this part is an excellent choice.

5. Tachometer

A faulty engine speed sensor could be a cause for numerous problems in your vehicle. It's a vital component of your Audi's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is rotating. If this sensor fails, it can cause problems for the transmission as well as the other car's components.

The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via a more info grey wire. The ECU then processes this signal to control the flow of fuel, timig and boost and then transmitting it to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and check here pin T26a/12. You should detect the resistance to be around 1000 ohms between these points. This part is common across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 Du So, you may find them in wrecking yards.