The 10 Worst Audi G28 Fails Of All Time Could've Been Prevented

How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission just above the flywheel ring gear. It transmits a signal the ECU via a grey 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 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 utilizes this information to regulate 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 point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors according to the situation.

If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing can be a bit difficult since there are two connector pins and they perform different functions but the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read about 1000 ohms. If you're experiencing issues with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant decrease in power. It was like the engine had run out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs. Three were drenched with gazoline the 4th one was dry. When I crank the engine with no sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I assume that the problem is elsewhere.

I also tried to reset the PID with no success. The car can start when the G28 is unplugged and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 get more info bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, but i believe that i've completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone check here has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is similar 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 click here a parts store. It is simple to test them - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make a decision about timing get more info 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 you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.

A damaged G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire while in gear. It is probable that your sensor is failing and requires to be replaced if you encounter any of these symptoms. The good thing is that they are very cheap and easily accessible particularly if you're looking at an Bosch model, like ours. Alternately, the GM version of this unit is also a good choice.

5. Tachometer

A failing engine speed sensor could be the cause of numerous issues with your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is spinning. If this sensor fails, it will cause problems for the transmission, as well as the other car's components.

The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU then processes the signal to control the flow of fuel, timig and boost, and also sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between those points. This is a common component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in read more wrecking yards.