How to Replace an audi key fob G28 Engine Speed Sensor

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

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.

The sensor is used as a reference point to connect 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 accordingly.

If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumped chain link in the upper chain. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

It's a bit 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. If the sensor is operational, it should be reading around 1000 ohms. If you're experiencing issues with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is running out of gas or the injectors aren't firing anymore. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the fourth 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 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 got zero Ohm. Therefore, i think the issue is somewhere else.

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 problem persists 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 bars when the actual pressure is zero.

I'm not certain what to do, i think i've pretty much eliminated everything else. But i am afraid I may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. It is simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.

A damaged G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. If you experience any of these problems, it is likely your sensor is going bad and requires replacement. They are cheap and easy-to-find, especially when they're a Bosch unit like ours. You can also choose the GM version of this component is also a great option.

5. Tachometer

A malfunctioning engine sensor can cause a number of problems in your vehicle. It is a crucial part of your audi a3 key fob replacement's transmission, as it sends information to the ECU about how the car's crankshaft is spinning. When this sensor fails, it could disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate the flow of fuel, timig and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should see approximately 1000 ohms of resistance between those two pins. This is a typical component across the audi replacement car keys tt audi key replacement cost fob (on front page) 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.