20 Myths About Audi G28: Debunked

How to Replace an replacement audi key fob key shell (information from www.google.at) G28 Engine Speed Sensor

Charles the Humble Technician teaches you 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 sends a signal to the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).

It is a little tricky to test as there are several connector pins, and each one has different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading about 1000 ohms. Check 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 a high speed I noticed a massive drop in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs, three were drenched in gazoline, the fourth one was dry. When I crank the engine with no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stay closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero Ohm. I assume that the problem is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.

I'm not certain what to do, but i feel i have pretty much completely ruled out all other possibilities. However, i'm afraid that I might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or 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 at the connector end facing up). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner that could cause engine shut down.

Some of the signs of a failing G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or a misfire when you're in gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these signs. The good thing is that they are very affordable and easily accessible particularly if you're looking at the Bosch unit like ours. If you prefer, GM's version of this part would be an excellent choice.

5. Tachometer

A damaged engine sensor could cause a number of problems within your vehicle. It's a crucial component of the transmission in your audi keyless go because it relays information to the ECU on how fast or slow the engine is spinning. If this sensor fails, it can affect 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 just above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to control the amount of fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can check 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 detect the resistance to be around 1000 ohms between these points. This is a common feature across the replacement audi key fob 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find them in wrecking yards.