Audi G28: The Good The Bad And The Ugly

How to Replace an audi smart key replacement G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located near the edges of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49), then to the tachometer in 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 a signal to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer within the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu has to 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, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).

It can be a bit difficult to test because there are several pins on the connector and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is 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, when accelerating from highway paytoll at full speed I noticed a significant 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 with gazoline the fourth one was dry. When I start the engine with no sparks i put tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th stay closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero Ohm. I'm assuming that the issue is elsewhere.

I also tried to reset PID without success. The car is able to start when the G28 is not plugged in and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I think I've eliminated everything else. I'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

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

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft to make decisions regarding timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could lead to an engine shutdown.

The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter 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 should be replaced. They're cheap and easy to find, especially in the case of an Bosch unit like ours. Alternatively, the GM version of this part is also a great option.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for many issues with your vehicle. It's a vital component of the Audi car key Holder's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is turning. This sensor could cause the transmission to fail and other car key cover audi components to be affected.

The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU then uses and processes this 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 test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) as well as between T6a/1, audi replacement key a1 key fob (https://xypid.win/story.php?title=the-Myths-and-facts-behind-audi-a5-replacement-key) and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these points. This is a typical part that is found across the audi replacement keys 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.