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 edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through the grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indicator to the G5 Tachometer within the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
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 provided by other sensors (G4 or G40).
Testing is a bit tricky since there are two pins for the connector and they have different functions but the most effective method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. Check for signs of coolant, or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced massive power loss like the engine is out of gas or injectors are not firing any more. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. I placed a tissue over each hole in the injector and when i turn the engine on without sparks, the 3 with gazoline jump right out. The fourth one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is elsewhere.
I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value that is -49c even after unplugging it. Also i noticed that the gauge for website oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. I'm afraid i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel audi replacement keys Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is the same as the G4 and they both work in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is simple to test them - just switch your DMM into resistance mode and test 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 ADU) engines must know the position and speed of the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
The signs of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal, and/or a misfire when you're in gear. If you have any of these problems, it is likely your sensor is deteriorating and needs replacing. The good thing is that they are quite affordable and readily available, especially if you're looking at an Bosch unit which is what ours are. You can also choose the GM version of this unit is also a great option.
5. Tachometer
A failing engine speed sensor could be the reason behind a slew of issues with your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is rotating. If the sensor fails, it can affect the performance of the transmission and check here the other car's components.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via more info pin T6a/1 (trace click here [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms between these points. This is a typical part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.