How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. lost my audi car keys is situated on the outside of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult as there are two different connector pins and they have different functions but the best method to test it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms when it is operating at its maximum. Check for evidence of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge drop in power. It was as if the engine was running out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs. Three were drenched in gazoline, the 4th one was dry. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the ones with gazoline jump out. The 4th one remains closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is elsewhere.
I also tried to reset PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do. I feel like i've pretty much ruled everything else out. But replace audi key 'm worried that I may 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 sent from the RPM sensor. The GM-style sensor is the same as the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is simple to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go badly, you will see codes on the diagnostic scanner which can cause the engine to shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. If you are experiencing any of these problems, it is likely your sensor is failing and should be replaced. They are cheap and easy-to-find, especially when they're a Bosch model like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It's an essential component of the transmission of your Audi since it sends information to the ECU on how fast or slow the engine of the car is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via a grey wire. The ECU then uses and processes this signal to regulate fuel, timig and boost as well as transmitting it to the G5 Tachometer located in the 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 via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.