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 situated near the transmission's edge, above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. replacement audi key uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. new audi car key means that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test as there are different connector pins, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is at full operation. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive reduction in power. It was like the engine had run out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was unclean. I placed a tissue over each injector hole, and when I turn the engine on without sparks, the ones with gazoline jump right out. The 4th one stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID but without success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However the intermittent misfire issue persists at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is zero.
I don't know what to do. I believe that I've eliminated everything else. However, i'm afraid that I may have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. Test them out to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that has to know the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. To do this, it utilizes 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 display codes that could cause an engine shutdown.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when you are in gear. If you experience any of these problems, it is likely your sensor is failing and should be replaced. They are cheap and easy-to-find particularly in the case of an Bosch model like ours. If you prefer, GM's version of this part is an option.
5. Tachometer
A failing engine sensor could cause a variety of issues in your vehicle. It is an important part of the transmission in your Audi, as it transmits information to the ECU on how fast or slowly the car's engine is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU then processes this signal to control fuel, timig, and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can examine the continuity between pins 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 see an average resistance of 1000 ohms between these two points. This is a standard part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.