How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated on the outside of the transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within 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 a signal to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.

If this sensor fails to function, the ECU will display a P00160 error code. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper timing chain. However the code will not 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 serve different purposes but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms when it is in full operation. Examine for signs of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced massive power loss as if the engine was running out of gas or injectors aren't firing anymore. Today, i pulled out the spark plugs. Three were drenched in gazoline, the fourth one was dry. I placed a tissue over each hole in the injector and when I turn the engine on without sparks, the three that have gazoline pop right out. The 4th one stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I assume that the problem is elsewhere.

I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in replacement key for audi a3 the cockpit shows 2 bars while the actual pressure is 0.

I'm not certain what to do, but i think i've pretty much eliminated everything else. However, i'm afraid that I might have missed something. If anyone has any ideas 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 operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. Testing them is easy - put your DMM in resistance mode spare audi key and take audi a3 replacement key measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to know the position and speed of the crankshaft to check here make decisions regarding timing of the fuel injectors, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.

The audi tt keys signs of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when in gear. If you have any of these problems, it is most likely that your sensor is going bad and requires replacement. They're cheap and easy to find especially in the case of an Bosch model like ours. Alternatively, the GM version of this part is also a good choice.

5. Tachometer

A damaged engine sensor could cause a myriad of issues within your vehicle. It's an essential component of your Audi's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. This sensor can 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, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. You can also examine the continuity between pins 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 approximately 1000 ohms resistance between those points. This part is common across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du You may also find good ones in wrecking yards.