How to Replace an Audi tt key replacement G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge just above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends signals to the G5 tachometer inside the instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu must be aware 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 to function, 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 a chain stretch or a jump in the chain link of the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging as there are two different connector pins and they perform different functions however the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is operational, it should be reading around 1000 ohms. If you are having problems with this part, check for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth was dry. I placed a tissue over each injector hole and when i start the engine without sparks, the three with gazoline jump out. The fourth one remains closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. Therefore, i think the issue is in another place.

I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.

I'm not certain what to do, as i believe that i've completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. It is simple to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft to determine timing of 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 sensors, the diagnostic scanner will show codes that could cause an engine shut down.

Some of the signs of a failing G28 sensor are an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when in gear. It is probable that your sensor is failing and requires to be replaced if you experience any of these symptoms. The good thing is that they are quite affordable and easy to find particularly if you're looking at a Bosch unit like ours. Alternatively, GM's version of this component is an excellent choice.

5. Tachometer

A failing engine speed sensor could be the reason behind a slew of problems in your vehicle. It's a vital component of the replacement audi a4 key's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. If the sensor fails, it could disrupt the performance of the transmission and the other car's components.

The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU is then able to process this signal to control fuel, timig, and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can test the sensor for Audi A1 Car Key failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those points. This is a typical part that is found across the audi key fob 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.