How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission, above the flywheel gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.
If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult as there are two different connector pins, and they serve different purposes however the best way to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should read approximately 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at a high speed, i noticed a huge drop in power. It was like 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 one was dry. When I start the engine, there are no sparks i put tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is not plugged in and runs fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.
I'm not certain what to do, but i feel i have pretty much eliminated everything else. However, i'm afraid that i might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. It is simple to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft to determine fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shut down.
A failing G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, or a misfire in gear. It is likely that your sensor is failing and needs to be check here replaced if you encounter any of these signs. The good news is that they are very affordable and easily accessible particularly in the case of an Bosch unit which is what ours are. You can also choose the GM version of this component is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of numerous issues in your vehicle. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU on how fast or slow the website engine of the car is spinning. This sensor can cause the transmission to fail and other components in the car to be affected.
The G5 engine sensor is located at the edge of the read more transmission, just above 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 regulate fuel, timig, and boost, and also transmitting it to get more info the G5 tachometer in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect more info the resistance to be around 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.