How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located at the edge of transmission over the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, just above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC and also the location of the camshaft in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumpy chain link in the upper chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).
how do i get a replacement key for my audi 's a bit tricky to test because there are several pins on the connector, 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 approximately 1000 ohms when the sensor is in full operation. If you're having issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed, i noticed a huge decrease in power. It was like the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. When I crank the engine, there are no sparks i put tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th one stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. So i assume the problem is in another place.
I also tried to reset the PID but without success. The car can start when the G28 is disconnected and is running fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows an ice temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, as i believe that i've ruled out everything else. I'm concerned that i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's 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 has to know the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these sensors, the diagnostic scanner will display codes that could lead to the engine shutting down.
A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, or a misfire in the gear. It is probable that the sensor is failing and needs to be replaced if you experience any of these signs. The good news is they are very affordable and easy to find, especially in the case of a Bosch model, like ours. You can also choose the GM version of this part is also a good choice.
5. Tachometer
A failing engine speed sensor could be a cause for many problems in your vehicle. It's a crucial component of the transmission of your Audi since it sends information to the ECU on how fast or slowly the car's engine is turning. This sensor could cause the transmission to fail and other components in the car to be affected.
The G5 engine speed sensor is situated on the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to control the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between those two pins. This is a common part across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.