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 situated near the transmission's edge over the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jump in the chain link of the upper chain. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging because there are two connector pins, and they serve different purposes but the most effective method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is fully functional, it should read around 1000 ohms. If you're having 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 reduction in power. It was as if the engine was running out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each of the injector holes, the 3 drenched with gazoline pop out, but the 4th one stays shut. I tried check here to test the ground connections of ECU pins 14,30, and 48/55. I got 0ohm. I'm assuming the issue is elsewhere.
I also tried to reset the PID but without success. The car can start when the G28 is unplugged and it runs perfectly when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. website I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not sure what to do, but i believe that i've completely ruled out all other possibilities. I'm concerned that i may have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, get more info and RS2 vehicles. read more You can easily locate the spare in a salvage shop or parts store. It is simple to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will show codes that could cause an engine shut down.
A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or a misfire in gear. If you are experiencing any of these issues it is likely that your sensor is deteriorating and requires replacement. They are cheap and easy-to-find particularly in the case of an Bosch unit like ours. Alternately, the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues within 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 car's engine is spinning. If this sensor fails, it could affect the performance of the transmission as well as the other car's components.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU then processes the signal to control the flow of fuel, timig and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin check here T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between those points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find them in wrecking yards.