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 on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, directly above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC and also where the camshaft lies in order to activate the spark and injectors.
If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in 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 because there are two connector pins and they serve different purposes but the most effective method to test it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading approximately 1000 ohms. If you are having problems with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth one was dry. I put a piece of tissue over each injector hole and when I start the engine with no sparks, the three with gazoline jump out. The fourth one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I think the issue is in another location.
I also tried to reset the PID but without success. The car is able to start when the G28 is not plugged in and is running fine when it is plugged in but it still has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, but i think i've pretty much completely ruled out all other possibilities. But i'm worried that i might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. It is simple to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must know both the position and speed the crankshaft click here in order to make a decision about timing of the fuel injector, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will show codes that could lead to get more info the engine shutting down.
Some of the symptoms of a failing G28 sensor are an inaccurate rev counter in the gearbox and gears that shift faster than normal, and/or a misfire when you are in gear. It is audi tt keys possible that your sensor is failing and needs to be replaced if you encounter any of these symptoms. They're inexpensive and easy to locate especially in the case of an Bosch unit like ours. If you prefer, GM's version of this component is an option.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. When this sensor fails, it will disrupt the performance of the transmission as well as the other car's components.
The G5 engine sensor read more is located near the edge of the transmission, over the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. The ECU is then able to process this signal to click here regulate fuel, timig, and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is a standard 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.