Audi G28: The Good The Bad And The Ugly

How to Replace an replacement key audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on 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 signals to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends signals to the G5 tachometer inside 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 the position of the camshaft, to trigger the spark and injectors.

If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test as there are different connector pins, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when it is operating at its maximum. If you're experiencing issues with this sensor, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had a big cut in power like the engine is out of gas or injectors are not firing any more. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. When I start the engine, there are no sparks i put tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I think the issue is elsewhere.

I also tried to reset the PID but without success. The car is able to start if the G28 is disconnected and is running fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a temperature of -49c. 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, i feel i have pretty much completely ruled out all other possibilities. I'm concerned that i may have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by 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 find the spare in a salvage shop or a parts store. Test them out - put your DMM in resistance mode and take measurements 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 of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.

A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, and/or an unfire when in the gear. It is probable that your sensor is failing and needs to be replaced if you notice any of these symptoms. The good thing is that they are very affordable and easily accessible, prices especially in the case of a Bosch model, like ours. Alternatively, GM's version of this component is an excellent choice.

5. Tachometer

A failing engine speed sensor could be the cause of numerous issues with your car. It's an essential component of the transmission in your audi spare key replacement since it sends information to the ECU regarding how fast or slowly the engine is turning. When this sensor fails, it can cause problems for the transmission and the rest of the car's components.

The G5 engine speed sensor is located at the edge of the transmission, above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via a grey wire. The ECU then processes the signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This is the same across the audi Car key replacement cost 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU, so you might find good ones in wrecking yards.