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 at the edge of transmission just above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located 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 fuel, timig and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.
If this sensor fails, the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging as there are two different connector pins, and they perform different functions but the most effective method to test it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read about 1000 ohms. If you're having issues with this component, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced massive power loss like the engine is running out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was unclean. I put tissue over each injector hole and when i turn the engine on without sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming that 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 works fine when the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The coolant temperature sensor (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 bars but the actual pressure is 0.
I don't know what to do. I think I've all other possibilities out. I'm worried that i might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by audi a3 key replacement 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 so you can easily find one at a junkyard or in a local parts store. It is easy to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's audi a1 key end facing up). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of replacement key for audi a4 the crankshaft in order to make a decision about timing of the fuel injector, for example. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will display codes that could lead to an engine shut down.
A malfunctioning G28 sensor can cause an inaccurate speed counter for the gearbox, here a gearbox that shifts faster than normal, or a misfire in gear. If you experience any of these issues, it is likely your sensor is failing and should be replaced. The good thing is that they are very affordable and easy to find, especially when you're looking at an Bosch model, like ours. Alternately, the GM version of this component is also a great option.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind a slew of issues in your vehicle. It's an essential component of the Audi's transmission because it communicates to the ECU about how the car's crankshaft is spinning. If get more info this sensor fails, it can cause problems for the transmission and the rest of the car's components.
The G5 engine speed sensor is located on the outside of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes the signal to control fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between these two points. This is a typical component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.