How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using an uncolored wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC, and where the camshaft lies to trigger the spark and injectors.
If this sensor fails to function, 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 jumpy chain link in the upper chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test as there are various connector pins, 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 approximately 1000 ohms when it is operating at its maximum. If you're having issues with this component, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss like the engine is running out of gas or injectors aren't firing anymore. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. I placed a tissue over each injector hole, and when i turn the engine on without sparks, the ones with gazoline jump out. The fourth one remains shut. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero Ohm. I'm assuming the issue is somewhere else.
I also tried to reset the PID without success. The car is able to start if the G28 is unplugged and it runs perfectly when it is plugged in but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when unplugged, still shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do. I believe that I've ruled everything else out. But i'm worried that I might have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. Test them out to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft to make a decision about fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.
Some of the signs of a failing G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. If you experience any of these issues it is likely that your sensor is failing and should be replaced. The good thing is that they are quite affordable and easy to find particularly in the case of a Bosch model, which is what ours are. Alternately, the GM version of this component is also a good choice.
5. Tachometer
A damaged engine sensor could cause a number of problems in your vehicle. It's a crucial component of the transmission of your Audi since it sends information to the ECU about how fast or slow the car's engine is spinning. When this sensor fails, it could cause problems for the transmission and the other car's components.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. The ECU then processes this signal to regulate fuel, timig, and boost and then sends it on to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Also, 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. Audi A1 keys thekeylab.co.uk should detect an average resistance of 1000 ohms between these points. This is a standard component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.