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, above the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using a grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware 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 indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper timing chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test because there are different pins on the connector, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is operating at its maximum. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were soaked with gazoline and the fourth was dry. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is somewhere else.
I also tried to reset PID without read more success. The here car can start when the G28 is not plugged in and it runs perfectly when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.
I'm not certain what to do, as i believe that i've completely ruled out all other possibilities. But i am afraid i might have missed something. If anyone has any suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump in the website g28 is activated by a signal sent by the RPM sensor. The GM-style sender 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 salvage yard or at a parts store. Test them out by website putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine 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 while in gear. If you experience any of these problems, it is likely your sensor is going bad and requires replacement. They're inexpensive and easy to locate especially if they're a Bosch unit like ours. Alternately, GM's version this part would be a good option.
5. Tachometer
A faulty engine speed sensor could be the cause of numerous issues with your car. It's a crucial component of the transmission in your Audi since it sends information to the ECU on how fast or slow the engine is spinning. If the 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 located at the outside of the transmission just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to control fuel and boost, as well as timig. It also relays 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. You can also check continuity check here between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those points. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du So, you may find some good ones in wrecking yards.