How to Replace an audi tt key programming G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is located on the outside of the transmission, above the flywheel gear. It sends a message to the ECU through 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 edge of transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer in the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC, and the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit tricky since there are two connector pins, and they have different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when it is in full operation. If you're experiencing issues with this component, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday accelerating full speed from 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. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth was dry. When i crank the engine with no sparks i put tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stay closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. I assume that the problem 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 continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.

I don't know what to do. I feel like i've pretty much ruled everything else out. I'm concerned that i may have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or at a parts store. Testing them is easy - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and audi tt key programming 2 (2nd from left on the black connector's end). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will display codes that could cause the engine shutting down.

Some of the symptoms of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal, and/or a misfire when you're in gear. If you experience any of these problems, it is most likely that your sensor is going bad and needs replacing. They're inexpensive and easy to locate, especially when they're a Bosch unit like ours. Alternatively, the GM version of this component is also a good option.

5. Tachometer

A faulty engine speed sensor could be a cause for numerous problems in your vehicle. It's a vital component of the audi replacement keys's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor can cause the transmission to fail and other components in the car to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then processes this signal to control fuel, timig and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can test for sensor failure by examining the continuity of 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 [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is a common part that is found across the audi a3 key replacement 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.