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 near the transmission's edge over the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU uses this information to control boost and fuel. It also sends an indication to the G5 tachometer in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC and also where the camshaft lies so that it can 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 be a sign of an issue with the chain or a jumpy chain link in the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Highly recommended Internet page is a bit challenging because there are two connector pins and they have different functions however the best method to test it is to measure resistance between the sensor and the ECU. When the sensor is fully functional, it should read approximately 1000 ohms. Check for signs of coolant or oil in the connector bay if you have issues with this component.
2. what to do if you lose your audi key , while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is out of gas or injectors are not firing any more. In the morning, i removed the spark plugs, three were drenched in gazoline, the fourth was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stay closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. So i assume the problem is somewhere else.
I also tried to reset the PID but with no luck. The car is able to start if the G28 is not plugged in and it runs perfectly when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. But i am afraid i might have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a junkyard 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 connector's side). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make decisions regarding fuel injector timing etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will show codes that could lead to an engine shutdown.
The signs of a failed G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when you're in gear. It is probable that the sensor is failing and needs to be replaced if you encounter any of these signs. They are cheap and easy-to-find especially in the case of a Bosch model like ours. Alternately, the GM version of this unit is also a good choice.
5. Tachometer
A faulty engine speed sensor could be the reason behind many issues with your vehicle. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it could affect the performance of the transmission, as well as the other car's components.
The G5 engine speed sensor is located at 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 uses this signal to control the flow of fuel and boost and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these two points. This is a common part 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.