How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two connector pins and they have different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should read about 1000 ohms. If you're having issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the 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. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth was dry. I put a piece of tissue over each injector hole, and when i start the engine without sparks, the ones with gazoline jump right out. The 4th one remains shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero ohm. So i assume the problem is somewhere else.
I also tried to reset the PID but without success. The car will audi replacement key start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows website 2 bar but the actual pressure is zero.
I'm not sure what to do. I think I've ruled everything else out. I'm concerned that i may have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is simple to test them to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They should be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that has to know the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox the gears are shifting faster than normal, and/or a misfire when in gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is that they are quite affordable and easily audi keys accessible particularly if you're looking at an Bosch model, which is what we have. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of issues in your vehicle. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU on how fast or slowly the car's engine is spinning. If the sensor fails, it could cause problems for the transmission, as well as the other car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends a replacement audi car key signal via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to control fuel, timig and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster here (trace [79]) and between pin T6a/1 as well as pin T26a/12. It should show approximately 1000 ohms of resistance between those points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du So, you may find some good ones in wrecking yards.