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How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge over the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU uses this information to control the amount of fuel and boost. It also sends signals 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 located so that it can start spark and injectors accordingly.
If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two pins for the connector and they have different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when it is at full operation. If you're experiencing issues with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a significant decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs. Three were drenched with gazoline the fourth was dry. When i crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming that the issue is somewhere else.
I also tried to reset PID without success. The car can start if the G28 is not plugged in and runs fine when it is plugged in however it has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, as i think i've pretty much ruled out everything else. I'm afraid i may have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft to make a decision about timing of the fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will show codes that could cause an engine shut down.
A malfunctioning G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or an unfire when in gear. If you experience any of these problems, it is most likely that your sensor is deteriorating and needs replacing. similar internet page is they are very affordable and easy to find particularly when you're looking at an Bosch model, which is what we have. Alternatively, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It's an essential component of the transmission in your Audi since it sends information to the ECU on how fast or slow the car's engine is turning. If this sensor fails, it can affect the performance of the transmission as well as the other car's components.
The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits signals via a gray wire to the ECU pin T55/49. The ECU then processes the signal to control the flow of fuel, timig and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms resistance between these two 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.