How to Replace an audi key fob G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.

If this sensor fails, the ECU will throw 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 timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

It's a bit tricky to test since there are several pins on the connector and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should read approximately 1000 ohms. Check for signs of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a massive decrease in power. It was like 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 4th one was dry. I placed a 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 14/55/30/55/48/55/14/55/48/ i get zero ohm. Therefore, i think the issue is somewhere else.

I also tried to reset the 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 issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.

I don't know what to do. I believe that I've eliminated everything else. I'm concerned that i may have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.

The signs of a failed G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when you are in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They are cheap and easy-to-find, especially when they're a Bosch sensor like ours. Alternatively, the GM version of this component is also a great option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues within your vehicle. It is an important part of the transmission in your audi a5 key fob since it sends information to the ECU on how fast or Audi Spare key cost slowly the car's engine is turning. If this sensor fails, it could disrupt the performance of the transmission as well as the rest of the car's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU then processes the signal to control fuel, timig and boost and then sends it on to the G5 Tachometer located in the instrument cluster. You can check 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 [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is the same across the audi tt key fob not working 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du So, you may find them in wrecking yards.