7 Small Changes That Will Make The Biggest Difference In Your Audi G28

How to Replace an audi a3 spare key G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace audi key 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 the grey wire (T55/49) and then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using the grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also where the camshaft lies in order to activate the spark and injectors.

If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper chain of timing. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging since there are two connector pins, and they serve different purposes however the best way to test it is to measure resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is at full operation. Check for signs of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced an abrupt drop in power like the engine is running out of gas or injectors are not firing at all. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was unclean. When I crank the engine without sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline pop out, but the 4th stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. So i assume the problem is in another place.

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

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

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or parts store. It is simple to test them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go badly, you will see codes on the diagnostic scanner which could cause engine shut down.

The signs of a failed G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when you're in gear. If you experience any of these problems, it is likely that your sensor is failing and needs replacing. The good thing is that they are very cheap and easily accessible particularly in the case of a Bosch sensor, which is what ours are. If you prefer, GM's version of this part would be an option.

5. Tachometer

A faulty engine speed sensor could be a cause for numerous problems in your vehicle. It's an essential component of the transmission in your audi smart key replacement since it sends information to the ECU about how fast or slow the car's engine is turning. If the sensor fails, it will disrupt the performance of the transmission and the rest of the car's components.

The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU utilizes this signal to control fuel and boost, as well as timig. It also sends it to the G5 Tachometer in instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin 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. It should show approximately 1000 ohms resistance between those two pins. This is a standard part across the Audi Key Copy 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.