How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper timing chain. 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 connector pins, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is in full operation. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors are not firing any more. I pulled out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. I put tissue over each injector hole and when i turn the engine on without sparks, the 3 with gazoline jump out. The fourth one remains closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. I assume that the problem is somewhere else.
I also tried to reset more info the PID with no success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed get more info that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. But i'm worried that I might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or a parts store. It is simple to test them by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's side). They should be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to determine fuel injector timing, etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes bad you will get codes on the diagnostic scanner that could cause engine shut down.
A failing G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, or a misfire in the gear. It is likely that your sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find especially in the case of an Bosch model like ours. If you prefer, GM's version of this part would be a good option.
5. Tachometer
A failing engine sensor could cause a myriad of issues within your vehicle. It's an essential component of your Audi's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is rotating. If the sensor fails, it could disrupt the performance of read more the transmission, as well as the other car's components.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU then uses and processes this signal to regulate fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can more info check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those two pins. This is a audi a4 key replacement standard component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.