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. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC, and the location of the camshaft to trigger the spark and injectors.

If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing can be a bit difficult as there are two different connector pins, and they perform different functions however the best method of testing it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is in full operation. Examine for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced massive power loss like the engine is running out of gas or the injectors are not firing any more. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the fourth was unclean. When I crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is in another place.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c, even if I unplug it. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do, as i think i've pretty much ruled out everything else. I'm afraid i may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is easy to test them: simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft to make a decision about fuel injector timing etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these, the diagnostic scanner will show codes that could cause an engine shutdown.

A damaged G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, and/or an unfire when in the gear. If you experience any of these issues it is likely that your sensor is failing and needs replacing. They're cheap and easy to find, especially in the case of an Bosch sensor like ours. Alternately, the GM version of this unit is also a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your car. It is a crucial part of your audi a3 keys's transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components in the car to be affected.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits signals via an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test the sensor for Audi replacement key any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms between these two points. This is a common feature across the audi replacement key [https://www.question-ksa.com/] 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU You may also find good ones in wrecking yards.