Audi G28: The Good The Bad And The Ugly
How to Replace an key audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the edges of the transmission above the flywheel ring gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using an uncolored wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.
If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).
It can be a bit difficult to test since there are various connector pins, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is operating at its maximum. If you're having issues with this sensor, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced massive power loss like the engine is running out of gas or injectors aren't firing at all. I pulled out the spark plugs this morning, three were soaked with gasoline and the 4th was dry. When i crank the engine with no sparks i put tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th stay shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I assume that the problem is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, as i think i've pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. Let me know If you have any suggestions! 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 identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the speed and position of the crankshaft to determine timing of the fuel injector, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.
A damaged G28 sensor could cause an inaccurate speed counter for your gearbox or a gearbox that shifts more quickly than normal, or replacement key for audi a3 a misfire in the gear. If you experience any of these issues it is likely that your sensor is going bad and should be replaced. The good news is they are very affordable and easy to find, especially when you're looking at an Bosch unit which is what we have. Alternatively, GM's version of this part would be a good option.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It's a vital component of your audi Keys replacement cost's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. 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 for sensor failure by checking 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 as well as pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a common part that is found across the audi replacement key 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.