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 outside of the transmission over the flywheel gear. It transmits a signal to the ECU through 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, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors accordingly.
If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult since there are two connector pins and they have different functions but the best method to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. Look for signs of coolant, or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were drenched with gazoline the fourth was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature get more info of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I'm not sure what to do, as i feel i have pretty much eliminated everything else. However, i'm afraid that i might have missed something. If anyone has suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both lost audi key operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know both the speed and position of the crankshaft in order to make a decision about timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could cause an engine shutdown.
A failing G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or a misfire in the gear. It is possible that the sensor is failing and requires to be replaced if you experience any of these signs. They're inexpensive and easy to locate, especially in the case of an Bosch model like ours. Alternatively, the GM version of this part is also a good choice.
5. Tachometer
A damaged engine sensor could cause a number of problems in your vehicle. It's a crucial component of the transmission of your Audi because it relays information to the ECU regarding how fast or slow read more the engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU then processes this signal to control fuel, timig, and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 get more info (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is a common component across the Audi 80 100 200, UrS audi spare key and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.