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. The sensor is situated at the top of the transmission above the flywheel ring gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and the position of the camshaft, in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).
It can be a bit difficult to test since there are different pins on the connector, and they all have different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is operating at its maximum. Examine for signs of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive drop in power. It was like the engine had run out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were drenched with gazoline the 4th one was dry. When I start the engine with no sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62), even when it is unplugged, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure website is zero.
I'm not sure what to do, as i feel i have pretty much completely ruled out all other possibilities. However, i'm afraid that I may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is easy 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 up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.
A failing G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or a misfire while in the gear. It is possible that the sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find audi replacement car keys particularly in the case of a Bosch unit like ours. Alternatively, the GM version of this part is also a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many audi car key replacement issues in your car. It's an essential component of the transmission in your Audi, as it transmits information to the ECU about how fast or slowly the car's engine is spinning. When this sensor fails, it will cause problems for the transmission, as well as the rest of the car's components.
The G5 engine speed sensor is situated on the edge of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and processes this signal to read more regulate the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 DU You may read more also find them in wrecking yards.