10 Things You Learned In Kindergarden That'll Help You With Audi G28

How to Replace an audi lost key G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It transmits a signal the ECU via an uncolored wire (T55/49), then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, just above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.

If this sensor fails to function, the ECU will display an error code P00160. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumped chain link in the upper chain. The code won't show without the additional information supplied by other sensors (G4 or G40).

It can be a bit difficult to test as there are different pins on the connector 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 approximately 1000 ohms when it is in full operation. If you are having problems with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a massive decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were drenched with gazoline the fourth was dry. When i crank the engine without sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline jump out but the 4th stays closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I'm assuming the issue is somewhere else.

I also tried to reset the PID with no success. The car key cover audi can start when the G28 is not plugged in and is running fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do. I feel like i've pretty much ruled everything else out. I'm afraid i may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or a parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.

Some of the signs of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. It is possible that the sensor is failing and needs to be replaced if you experience any of these symptoms. They're inexpensive and easy to locate especially in the case of a Bosch sensor like ours. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A failing engine sensor could cause a myriad of issues within your vehicle. It's an essential component of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. If the sensor fails, it could cause problems for the transmission as well as the rest of the car's components.

The G5 engine sensor is located at 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 fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these two points. This is a standard component across the replacement audi connect key a4 key (visit my web site) 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.