How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, just above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC and also where the camshaft lies so that it can activate the spark and injectors.
If this sensor 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 the possibility of a chain stretch or jump in the chain link of the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test as there are different pins on the connector, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when it is at full operation. If you're having issues with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge reduction in power. It was like the engine was running out of gas. Or, my injectors were not firing. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. I put tissue over each hole in the injector and when I turn the engine on without sparks, the ones with gazoline jump right out. The 4th one remains closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID but without success. The car is able to start when the G28 is disconnected and runs fine when it is plugged in however it has the more info intermittent misfire issue at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i believe that i've get more info completely ruled out all other possibilities. However, i'm afraid that I might have missed something. If anyone has any suggestions, please share them! 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 audi key replacement on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. It is simple to test them to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.
A damaged G28 sensor could result in an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. It is probable that the sensor is failing and needs to be replaced if you experience any of these signs. They are cheap and easy-to-find particularly when they're a Bosch model like ours. You can also choose the GM version of this component is also a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for numerous issues in your vehicle. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine is turning. 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 just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU then processes this signal to regulate the flow of fuel, get more info timig and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Also, 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 T6a/1 and pin T26a/12. There should be a resistance of approximately 1000 ohms between these points. This is a standard component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones website could be available in wrecking yards.