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 located on the outside of the transmission over the flywheel gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU utilizes this information to regulate fuel and boost. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test since there are several pins on the connector, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant drop in power. It was like 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 fourth one was dry. I placed a tissue over each injector hole and when i start the engine with no sparks, the ones with gazoline jump right out. The fourth one remains closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found zero ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID but with no luck. The car is able to start if the G28 is unplugged and runs fine when it is plugged in however it has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.
I'm not sure what to do, i believe that i've eliminated everything else. I'm concerned that i may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
A damaged G28 sensor can cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or a misfire in gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these symptoms. They're cheap and easy to find particularly when they're a Bosch model like ours. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of numerous issues with your car. It's an essential component of the transmission in your Audi, as it transmits information to the ECU on how fast or slowly the engine of the car is spinning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer inside 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 [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. spare audi key cost is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find some good ones in wrecking yards.