The Three Greatest Moments In Audi G28 History

How to Replace an Replacement Audi A3 Key G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends an indicator 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 show a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test as there are different connector pins, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and fob the sensor. If the sensor is operational, it should read around 1000 ohms. Examine 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 maximum speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth was dry. When I crank the engine with no sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is disconnected and is running fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not certain what to do, but i feel i have pretty much eliminated everything else. But i am afraid I may have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or at a parts store. It is simple to test them - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to be aware of the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.

Some of 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 issues it is most likely that your sensor is deteriorating and Audi key fobs needs replacing. The good news is that they are quite affordable and easy to find, especially when you're looking at an Bosch sensor, which is what we have. Alternatively, the GM version of this part is also a great option.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues in your vehicle. It's an essential component of the audi advance key's transmission as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. When this sensor fails, it will cause problems for the transmission, replacement audi Key cost Uk as well as the rest of the car's components.

The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to control fuel and boost, and also timig. It also sends it to the G5 Tachometer located 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 to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is the same across the audi replacement keys 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 Du, so you might find them in wrecking yards.