10 Of The Top Mobile Apps To Audi G28 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. The sensor is situated at the top of the transmission above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC and also the position of the camshaft, in order to activate the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error message. 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 jumped chain link in the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit tricky as there are two different connector pins and they serve different purposes however the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading approximately 1000 ohms. Look for signs of coolant or oil in the connector bay if you have issues with this component.


2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were drenched in gazoline, the 4th one was dry. I placed a tissue over each hole in the injector and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one remains shut. I tested the ground connection of ECU pins 14,30 and 48/55. replacement key for audi a4 found zero ohm. I assume that the problem is somewhere else.

I also tried to reset PID but without success. The car will start when the G28 is not plugged in and runs fine when it is connected, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do. I think I've ruled everything else out. I'm afraid i may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or parts store. Testing them is easy to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.

4. ECU

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

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 you are in gear. If you have any of these issues it is likely that your sensor is going bad and needs replacing. The good news is that they are quite affordable and easily accessible particularly if you're looking at the Bosch unit which is what we have. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine sensor can cause a number of problems in your vehicle. It's an essential component of the transmission in your Audi since it sends information to the ECU about how fast or slow the engine is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.

The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate fuel and boost, as well as timig. It also relays it to the G5 Tachometer in instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. Additionally, 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 and pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU So, you may find some good ones in wrecking yards.