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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 on the edge of the transmission, above the flywheel ring gear. It sends 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 situated at the edges of the transmission, just above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to control fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor serves as a reference to correlate 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 trigger spark and injectors in the right way.
If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain is stretched or a jump link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test because 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. When the sensor is fully functional, it should read about 1000 ohms. Look for evidence of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is running out of gas or the injectors aren't firing at all. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth one was dry. I placed a tissue over each injector hole, and when I start the engine with no sparks, the ones with gazoline jump 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 think the issue is somewhere else.
I also tried to reset PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c even when i unplug it. 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, as i believe that i've ruled out everything else. But i am afraid I might have missed something. If anyone has any ideas please let me know! 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 a spare in a wrecking shop or a parts store. It is simple to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). 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 a decision about timing of the fuel injector, for example. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown.
A damaged G28 sensor could cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or a misfire in gear. If you have any of these issues it is likely your sensor is failing and requires replacement. They're inexpensive and easy to locate, especially if they're an Bosch sensor like ours. Alternately, the GM version of this part is also a good option.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues within your vehicle. It is an important part of the transmission in your Audi since it sends information to the ECU about how fast or slowly the engine of the car is spinning. When this sensor fails, it can disrupt the performance of the transmission, as well as the other car's components.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. genuine audi key replacement uk is then able to process the signal to control the flow of fuel, timig and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see an average resistance of 1000 ohms between these 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 the 1995 RS2 Du So, you may find good ones in wrecking yards.
