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 located at the edge of transmission, above the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using the grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer in the instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.

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

It is a little tricky to test because there are different pins on the connector and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is operating at its maximum. If you're having issues with this part, check for signs of coolant or oil 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. Today, i pulled out the spark plugs. Three were soaked with gazoline and the 4th one was dry. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the 3 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. Therefore, i think the issue is in another place.

I also tried to reset the PID but without success. The car can start if the G28 is not plugged in and runs fine when it is plugged in, but still has the intermittent misfire website issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.

I don't know what to do. I believe that I've eliminated everything else. I'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. Test them out - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injector, audi a4 key replacement for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will show audi a1 key replacement the codes that could trigger an engine shutdown.

Some of the symptoms of a failing G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when in gear. If you are experiencing any of these issues, it is most likely that your sensor is deteriorating replacement audi key and should be replaced. The good thing is that they are very affordable and readily available particularly when you're looking at an Bosch sensor, which is what we have. Alternatively, the GM version of this unit is also a good option.

5. Tachometer

A failing engine sensor could cause a number of problems within your audi spare key vehicle. It's an essential component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slowly the car's engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to regulate fuel and boost, and also timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity of 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 as well as pin T26a/12. There should be the resistance to be around 1000 ohms between these points. This part is common across the Audi 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU You may also find them in wrecking yards.