Audi G28: 10 Things I'd Like To Have Known Earlier > 연습

How to Replace an audi q7 replacement key G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge over the flywheel gear. It sends a message 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 edge of transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig 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 know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display an error code P00160. 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 jump in the chain link of the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

It can be a bit difficult to test because there are various pins on the connector and they all have different 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 the sensor is in full operation. Look for evidence of coolant or oil in the connector bay if there are issues with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is out of gas or the injectors are not firing anymore. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. When i crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th stay shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. So i assume the problem is somewhere else.

I also tried to reset PID without success. The car is able to start if the G28 is not plugged in and is running fine when it is connected however it has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas 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. However, i'm afraid that I might have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or at a parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and audi Key Programmer 2 (with the bump at the connector end facing up). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will show codes that could lead to the engine shutting down.

Some of the signs of a failing G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when you're in gear. It is possible that your sensor repair 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 when you're looking at the Bosch model, which is what we have. Alternately, the GM version of this part is also a great option.

5. Tachometer

A damaged engine sensor could cause a number of problems within your vehicle. It is a crucial part of your audi keyless entry's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. When this sensor fails, it can affect the performance of the transmission as well as the rest of the car's components.

The G5 engine speed sensor is situated on the outside of the transmission, above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to regulate the flow of fuel and boost and also timig. It also sends it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms between these points. This is a standard component across the audi tt Key case 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.