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 top of the transmission, above the flywheel ring gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC, and the location of the camshaft to trigger the spark and injectors.
If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are several connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Look for evidence of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced a big cut in power like the engine is out of gas or the injectors are not firing any more. I pulled out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. I put tissue over each hole in the injector and when I turn the engine on without sparks, the three that have gazoline pop right out. The 4th one stays shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I think the issue is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.
I'm not certain what to do, but i feel i have pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. It is simple to test them by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner which could cause engine shut down.
A failing G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or an unfire when in audi tt keys the gear. It is possible that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is that they are quite affordable and readily available particularly if you're looking at a Bosch sensor, which is what we have. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A faulty engine speed sensor could be a cause for many issues with your car. It's a vital component of your Audi's transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. When this sensor fails, it will cause problems for the transmission as well as the other car's components.
The G5 engine speed sensor spare audi key is situated on the outside of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes this signal to regulate fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument audi car key replacement cluster. You can check for sensor failure by examining the continuity from the sensor to here the tachometer. Additionally, you can verify 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. You should observe approximately 1000 ohms of resistance between those two pins. This is a standard part that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 audi convenience key ADU. Good ones might be availble in wrecking yards.