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How to Replace an Audi Tt Key Fob Not Working G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission just 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 fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

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

If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

It is a little tricky to test because there are different pins on the connector and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is in full operation. If you are having problems with this part, check for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at a high speed, i noticed a huge decrease in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. When i crank the engine with no sparks, I put a piece of tissue on the top of each hole in the injector 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 zero Ohm. I think the issue is elsewhere.

I also tried to reset the 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 issue persists at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.

I'm not sure what to do, as i feel i have pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. If anyone has any ideas please chime in! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. Test them out by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make decisions regarding fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner which could cause engine shut down.

Some of the signs of a failing G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or misfiring when you are in gear. If you are experiencing any of these issues it is most likely that your sensor is failing and needs replacing. The good news is that they are very affordable and easy to find, especially if you're looking at a Bosch model, which is what ours are. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine speed sensor could be the reason behind numerous issues in your vehicle. It's a vital component of your audi q5 key's transmission, since it relays information to the ECU about how the car's crankshaft is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.

The G5 engine speed sensor is situated on the outside of the transmission just above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU is then able to process the signal to control fuel, timig, Audi Tt key and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, 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 see an average resistance of 1000 ohms between these points. This is a common feature across the audi key shell 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find some good ones in wrecking yards.