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 the grey wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors in the right way.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins and they have different functions however the best method to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when it is in full operation. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge drop in power. It was like the engine was running out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs. Three were drenched with gazoline the fourth was dry. When i crank the engine without sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stay shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. So i assume the problem is in another place.
I also tried to reset PID but without success. The car is able to start when the G28 is disconnected and runs fine when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant read more sensor (G62) website even when it is unplugged, shows a temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I feel like i've pretty much ruled everything else out. I'm concerned more info that i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor 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 in a local parts store. It is simple to test them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to know the position and speed of the crankshaft to make decisions regarding fuel injector timing etc. In order to do this it uses 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 the codes that could trigger the engine shutting down.
A damaged G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, or an unfire when in the gear. If you experience any of these problems, it is likely that your sensor is failing and requires replacement. The good thing is that they are very affordable and easily accessible, especially when you're looking at a Bosch unit which is what ours are. Alternatively, the GM version of this unit is also a good option.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind a slew of issues with your car. It's a vital component of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is spinning. When this sensor fails, it will affect the performance of the transmission and the other car's components.
The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via a grey wire. The ECU is then able to process the signal to control the flow of fuel, timig and boost and then sends website it on to the G5 tachometer inside the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This part is common across click here the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 DU, so you might find them in wrecking yards.