How to Replace an
Audi A1 keys G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC and also where the camshaft lies in order to activate the spark and injectors.
If this sensor fails, the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and could indicate the chain stretching or a jump link on the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
It can be a bit difficult to test since there are several pins on the connector, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is operational, it should be reading around 1000 ohms. Look for signs of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, three were soaked with gazoline and the 4th one was dry. I put tissue over each injector hole and when I turn the engine on without sparks, the three with gazoline jump out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. I assume that the problem is in another location.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I feel like i've pretty much eliminated everything else. I'm concerned that i may have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from 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. It is easy to find the spare in a salvage
shop or parts store. It is simple to test them - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black end of the connector). They must be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must know the speed and position of the crankshaft to determine fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these, the diagnostic scanner will display codes that could lead to the engine shutting down.
A failing G28 sensor can cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or an unfire when in gear. It is possible that your sensor is failing and requires to be replaced if you notice any of these signs. They're cheap and easy to find especially when they're an Bosch sensor like ours. Alternately, the GM version of this unit is also a good option.
5. Tachometer
A failing engine sensor could cause a myriad of issues within your vehicle. It's a crucial component of the transmission in your
audi car key replacement since it sends information to the ECU about how fast or slowly the engine is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits signals via a gray wire to the ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig, and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a typical component across the
audi a3 spare key 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.
