How to Replace an programming audi key G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the edge of transmission just above the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer located on 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 a signal via the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an alert 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 must know when the crankshaft is TDC and audikey the location of the camshaft so it can start spark and injectors in the right way.

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

It is a little tricky to test as there are various pins on the connector and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is at full operation. Look for signs of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge reduction in power. It was as if the engine was running out of gas. Or my injectors were not firing. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. I put tissue over each hole in the injector and when I start the engine with no sparks, the ones that have gazoline pop right out. The 4th one remains closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. So i assume the problem is elsewhere.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.

I don't know what to do. I feel like i've pretty much ruled everything else out. I'm concerned that 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 from the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or at a parts store. Testing them is easy to do - just 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 ADU) engines needs to know both the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. 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 lead to engine shutdown.

A damaged G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or a misfire in gear. If you experience any of these problems, it is most likely that your sensor is failing and requires replacement audi a4 key. The good thing is that they are quite affordable and readily available, especially if you're looking at a Bosch sensor, like ours. Alternately, the GM version of this unit is also a good choice.

5. Tachometer

A damaged engine sensor could cause a myriad of issues in your vehicle. It's a vital component of the audi key shell's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is turning. This sensor can cause the transmission to malfunction and other components of the car to be affected.

The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU then processes this signal to regulate the flow of fuel, timig and boost as well as 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. You can also 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 see a resistance of approximately 1000 ohms in these areas. This is the same across the audi key fob 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU, so you might find some good ones in wrecking yards.