How to Replace an audi key programmer G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated at the top of the transmission above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, just above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication 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 must know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.

If this sensor fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper chain. The code will not appear without the additional information provided by other sensors (G4 or audi key shell audi replacement key cost key (bysee3.com) G40).

Testing is a bit challenging since there are two pins for the connector and they serve different purposes but the most effective method to test it is to measure resistance between the sensor and the ECU. If the sensor is functional, it should read around 1000 ohms. Check for signs of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced an abrupt drop in power as if the engine was running out of gas or the injectors are not firing any more. In the morning, i removed the spark plugs. Three were soaked with gazoline and the fourth was dry. I put a piece of tissue over each hole in the injector and when i start the engine with no sparks, the three that have gazoline pop right out. The 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming the issue is somewhere else.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.

I don't know what to do. I think I've ruled everything else out. But i am afraid I might have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80 100, 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is simple to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these, the diagnostic scanner will show the codes that could trigger an engine shutdown.

Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or a misfire when in gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these signs. The good news is they are quite affordable and readily available, especially when you're looking at an Bosch model, which is what ours are. Alternately, the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues within your vehicle. It's an essential component of the transmission in your key audi since it sends information to the ECU on how fast or slow the engine is turning. If this sensor fails, it will cause problems for the transmission as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check 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 on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is a typical part across the Audi New key 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.