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Where Are You Going To Find Audi G28 Be 1 Year From Today?
How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC, and where the camshaft lies in order to activate the spark and injectors.

If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper timing chain. However, audi replacement key won't 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 however the best method to test it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when it is at full operation. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced a big cut in power like the engine is out of gas or the injectors aren't firing any more. This morning i pull out the spark plugs, three were drenched with gazoline the fourth was dry. When I start the engine without sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th one stays closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. I think the issue is in another location.

I also tried to reset the PID but without success. The car can start if the G28 is disconnected and runs fine when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while 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. But i am afraid I might have missed something. If anyone has any ideas please chime in! 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 both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. It is easy to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed of the crankshaft to determine timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these, the diagnostic scanner will display codes that could lead to an engine shutdown.

Some of the signs of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or a misfire when you're in gear. If you experience any of these problems, it is likely that your sensor is failing and requires replacement. The good thing is that they are very affordable and readily available, especially if you're looking at the Bosch unit which is what we have. You can also choose the GM version of this component is also a good choice.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for many issues with your car. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slow the engine of the car is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.

The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to control the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. You can also 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 and pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.