How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU uses this information to regulate boost and fuel. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has 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 display a P00160 error code. This indicates that the Crank Shaft is out of sync 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. The code won't show without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test as there are several pins on the connector, and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should read about 1000 ohms. Examine for signs of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge drop in power. It was as if the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were drenched in gazoline, the fourth was dry. I placed a tissue over each hole in the injector and when I start the engine without sparks, the three that have gazoline pop right out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. I assume that the problem is somewhere else.
I also tried to reset PID but without success. The car will start here when the G28 is disconnected and it runs perfectly when it is plugged in however it has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. Also i noticed that the oil pressure gauge in the audi a1 key cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i feel i have pretty much completely ruled out all other possibilities. But i am afraid I might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The website GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is easy to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the position and speed of the crankshaft in order to make a decision about 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 go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.
A malfunctioning G28 sensor could cause an inaccurate gearbox speed counter or a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you have any of these issues it is likely your sensor is failing and requires replacement. They are cheap and easy-to-find particularly in the case of a Bosch sensor like ours. Alternately, GM's version this component is an excellent choice.
5. Tachometer
A failing engine speed sensor could be the reason behind numerous issues with your vehicle. It's a vital component of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is rotating. This sensor can cause the transmission to malfunction and other car components to be affected.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then processes this signal to regulate fuel, timig, and boost, and also sends it on to the G5 tachometer in the instrument cluster. audi replacement keys You can check for sensor failure by examining the 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 as well as pin T26a/12. There should be the resistance to be around 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU So, you may find read more some good ones in wrecking yards.