How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission, above the flywheel 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, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate boost and fuel. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test since there are various pins on the connector, and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading about 1000 ohms. If you're having issues with this sensor, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power as if the engine was running out of gas or the injectors aren't firing at all. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. I put a piece of tissue over each injector hole and when I start the engine with no sparks, the 3 with gazoline jump right out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. Therefore, i think the issue is in another place.
I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 if i crank up the engine.
I don't know what to do. I believe that I've ruled everything else out. I'm afraid i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent 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. It is easy to find a spare in a get more info wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. In order to do this it uses a Crank Position audi spare key Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger the engine shutting down.
Some of the get more info symptoms of a malfunctioning G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal, and/or check here a misfire when you're in gear. It is likely that the sensor is failing and needs to be replaced if you notice any of these signs. The good news is they are quite affordable and readily available particularly if you're looking at an Bosch sensor, which is what ours are. Alternatively, the GM version here of this component is also a great option.
5. Tachometer
A faulty engine speed sensor could be the reason behind many problems in your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU on how fast or slow the engine is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.
The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes this signal to control fuel, timig, and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can check continuity between pin 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 the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU You may also find good ones in wrecking yards.