How to Replace an audi a5 key fob G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via an uncolored wire. 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 for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors.

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

Testing is a bit tricky as there are two different pins for the connector and they have different functions however the best way to test it is by measuring resistance between the sensor and the ECU. When the sensor is fully functional, it should read around 1000 ohms. Check for signs of coolant or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is running out of gas or the injectors aren't firing at all. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the fourth one was dry. When I crank the engine with no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I assume that the problem is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor replacement key for audi a3 the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, i think i've pretty much eliminated everything else. I'm concerned that i may have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. It is easy to test them - just put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing up). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines must know both the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could lead to an engine shut down.

A damaged G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or a misfire while in gear. If you experience any of these problems, it is likely that your sensor is deteriorating and requires Replacement Audi a4 key. They're inexpensive and easy to locate particularly in the case of an Bosch unit like ours. Alternatively, GM's version of this part would be an excellent choice.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues in your car. It's a vital component of the audi a4 replacement key's transmission as it sends information to the ECU about how the car's crankshaft is spinning. This sensor could cause the transmission to fail and other components of the car to be affected.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to control the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin 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 observe around 1000 ohms of resistance between these two points. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 Du, so you might find some good ones in wrecking yards.