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 on the edge of the transmission above the flywheel ring gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors according to the situation.
If this sensor fails the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test since there are several pins on the connector and each has its own functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is at full operation. If you're having issues with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power as if the engine was running out of gas or the injectors aren't firing at all. audi car key took out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. I placed a tissue over each injector hole, and when i start the engine with no sparks, the 3 that have gazoline pop right out. The 4th one remains closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is in another place.
audi replacement car keys tried to reset the PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The coolant sensor (G62) even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not sure what to do, as i feel i have pretty much ruled out everything else. 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 on the g28 is activated by a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. It is easy to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or a misfire in gear. It is likely that your sensor is failing and requires to be replaced if you experience any of these symptoms. They're inexpensive and easy to locate, especially in the case of an Bosch model like ours. Alternatively, GM's version of this part is an excellent choice.
5. Tachometer
A damaged engine sensor could cause a variety of issues within your vehicle. It's a vital component of your Audi's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU is then able to process the signal to control fuel, timig, and boost and then transmitting it to the G5 tachometer inside 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. It should show approximately 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU You may also find them in wrecking yards.