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. This sensor is located on the outside of the transmission over the flywheel gear. It transmits 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 on the outside of the transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.

If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain stretching or a jump link on the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit tricky because there are two pins for the connector and they perform different functions but the most effective method to test it is to measure the resistance between the sensor and the ECU. If the sensor is functional, it should read approximately 1000 ohms. If you're experiencing issues with this component, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed, i noticed a huge reduction in power. It was like 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. When I crank the engine without sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I don't know what to do. I feel like i've pretty much ruled everything else out. But i am afraid i might have missed something. If anyone has any suggestions, please let me know! TIA!


3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is easy to test them - just switch your DMM into resistance mode and measure 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 ADU) engines requires to know both the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If audi q7 car key replacement are experiencing issues with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shut down.

Some of the symptoms of a failed G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when you are in gear. It is probable that your sensor is failing and requires to be replaced if you notice any of these signs. The good news is they are quite affordable and easy to find, especially when you're looking at an Bosch sensor, which is what ours are. You can also choose the GM version of this component is also a great option.

5. Tachometer

A failing engine sensor could cause a number of problems within your vehicle. It is a crucial part of the Audi's transmission as it sends information to the ECU about how the car's crankshaft is turning. If the sensor fails, it can affect the performance of the transmission and the rest of the car's components.

The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through a grey wire. audi lost key replacement to control the flow of fuel, timig and boost as well as transmitting it 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. Additionally, 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 pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This is a common feature across the Audi 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 some good ones in wrecking yards.