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How to Replace an audi keyfob G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an indicator to the G5 Tachometer within 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 where the camshaft is so it can trigger spark and injectors according to the situation.

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

It's a bit tricky to test since there are different pins on the connector and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is functional, it should read about 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant reduction 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 4th was dry. I placed a tissue over each hole in the injector and when I turn the engine on without sparks, the three with gazoline jump out. The 4th one stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got 0ohm. I assume that the problem is elsewhere.

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 continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c, even if I unplug it. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.

I don't know what to do. I think I've ruled everything else out. However, i'm afraid that i might have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent 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 locate an extra in a wrecking shop or parts store. It is simple to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injectors, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will show codes that could lead to an engine shutdown.

The signs of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when in gear. If you experience any of these issues it is most likely that your sensor is failing and requires replacement audi key fob. The good news is they are quite affordable and easy to find, especially when you're looking at the Bosch unit which is what we have. Alternatively, the GM version of this part is also a good choice.

5. Tachometer

A damaged engine sensor could cause a myriad of issues in your vehicle. It is a crucial part of your audi key programming's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. If this sensor fails, it will cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can test the sensor for failure by checking 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. It should show approximately 1000 ohms resistance between these two points. This is a common feature across the audi keyfob key copy [simply click for source] 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du So, you may find good ones in wrecking yards.