How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the humble mechanic demonstrates 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 the ECU via an uncolored wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, just above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
It is a little tricky to test as there are different connector pins, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. If the sensor is functional, it should read around 1000 ohms. If you are having problems with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the 4th was dry. I placed a tissue over each hole in the injector and when i start the engine without sparks, the three that have gazoline pop right out. The fourth one remains shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero Ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 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 all other possibilities out. I'm concerned that i may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The replacement key for audi a4 GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and take measurements 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 must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the position and speed the crankshaft to determine timing of the fuel injector, etc. It utilizes get more info a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either one of these, the diagnostic scanner will display codes that could lead to the engine shutting down.
Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter get more info in the gearbox the gears are shifting faster than normal and/or misfiring when you are in gear. It is possible replacement audi key that the sensor is failing and needs to be replaced if you notice any of these signs. The good news is they are quite affordable and readily available, especially when you're looking at the Bosch unit which is what we have. Alternatively, GM's version of this part would be an option.
5. Tachometer
A faulty engine speed sensor could be the cause of numerous problems in your car. It's an essential component of the transmission in your Audi because it relays information to the ECU about how fast or slow the engine is turning. If the sensor fails, it will cause problems for the transmission, as well more info as the other car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU uses this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between those points. This is the same 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 may find good ones in wrecking yards.