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 transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. audi replacement key uk uses this information to regulate fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors accordingly.
If this sensor fails the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging since there are two connector pins, and they serve different purposes but the most effective way to test it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should read about 1000 ohms. Check for evidence of coolant or oil in the connector bay if there are problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or injectors are not firing any more. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the 4th one was dry. When I start the engine with no sparks i put tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stay closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming the issue is in another place.
I also tried to reset PID but without success. The car will start if the G28 is not plugged in and it runs perfectly when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.
I don't know what to do. I feel like i've pretty much all other possibilities out. But i am afraid I might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or parts store. It is simple to test them - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's side). They should 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 in order to make decisions regarding timing of the fuel injectors, 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 one of these, the diagnostic scanner will display codes that could lead to the engine shutting down.
The signs of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or a misfire when you are in gear. If you have any of these problems, it is likely that your sensor is failing and needs replacing. The good news is that they are quite affordable and easily accessible particularly when you're looking at an Bosch sensor, which is what ours are. Alternately, GM's version this part would be an option.
5. Tachometer
A failing engine speed sensor could be the reason behind a slew of problems in your car. It's a vital component of your Audi's transmission, since it relays information to the ECU about how fast or slow the car's crankshaft is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear. It sends 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 then sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be the resistance to be around 1000 ohms between these points. This is a typical part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.