How to Replace an audi keyless entry G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission over the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49), then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via a grey wire. The ECU utilizes this information to regulate fuel and Audi Key Shell boost. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC and also the position of the camshaft, in order to activate the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error code. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

It can be a bit difficult to test because there are several pins on the connector, and each one has different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when it 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 had massive power loss like the engine is out of gas or injectors are not firing at all. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was dry. When i crank the engine, there are no sparks, i place a tissue on top of each injector hole 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 got zero ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID but with no luck. The car will start when the G28 is not plugged in and is running fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows temperatures 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, as i feel i have pretty much ruled out everything else. I'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor is the same as the G4 and both function in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is easy to test them - simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the position and speed of the crankshaft to determine timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will show codes that could cause the engine shutting down.

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

5. Tachometer

A faulty engine speed sensor could be a cause for many issues in your car. It is an important part of the transmission in your Audi A3 Spare Key since it sends information to the ECU on how fast or slowly the car's engine is spinning. When this sensor fails, it could cause problems for the transmission as well as the rest of the car's components.

The G5 engine speed sensor is located on the outside of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate the flow of fuel and boost as well as timig. It also sends it to the G5 Tachometer in instrument cluster. You can check replacement key for audi sensor failure by checking 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 [79]) and between pin T6a/1 and pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This part is common across the audi new key 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find some good ones in wrecking yards.