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How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig 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 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 when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper timing chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are different connector pins, and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is operating at its maximum. If you're experiencing issues with this component, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power like the engine is running out of gas or the injectors are not firing anymore. This morning i pull out the spark plugs, 3 were drenched with gazoline the 4th one was dry. When I start the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I assume that the problem is somewhere else.
I also tried to reset the PID but with no luck. The car is able to start when the G28 is not plugged in and runs fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not sure what to do. I believe that I've all other possibilities out. But i'm worried that I might have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. Testing them is easy to do - just put 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 end of the connector). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.
Some of the signs of a malfunctioning G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when you are in gear. If you are experiencing any of these issues it is likely that your sensor is failing and needs replacing. The good news is they are very cheap and readily available, especially when you're looking at an Bosch model, which is what we have. If you prefer, GM's version of this part is an option.
5. Tachometer
A failing engine speed sensor could be the reason behind many issues in your car. It is a crucial part of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the 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 [79trace [79]) and between pin T6a/1 and pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du So, you may find some good ones in wrecking yards.