How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located at the top of the transmission above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer within 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 a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky as there are two different pins for the connector and they perform different functions but the best method of testing it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. Check for evidence of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or the injectors aren't firing at all. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I placed a tissue over each injector hole and when i start the engine without sparks, the ones with gazoline jump out. The fourth one remains shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is somewhere else.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. check here The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed here that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I don't know what to do. I believe that I've eliminated everything else. I'm worried that i might have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and take measurements more info 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
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and click here an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shut down.
A failing G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, or a misfire in gear. It is likely that the sensor is failing and requires to be replaced if you experience any of these signs. The good news is that they are quite affordable and easily accessible particularly in the case of the Bosch sensor, which is what ours are. Alternatively, GM's version of this component is a good option.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of many issues with your vehicle. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU on how fast or slowly the engine of the car is spinning. If the sensor fails, it could affect the performance of the transmission as well as the other car's components.
The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to regulate the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer inside 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 on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should observe here approximately 1000 ohms of resistance between those points. This is a common feature 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 them in wrecking yards.