How to Replace an audi key fob G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located at the edge of transmission just above the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, above the flywheel ring. This sensor sends an electrical signal through 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 indication to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference point to audi connect key with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.

If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing can be a bit difficult since there are two pins for the connector and they perform different functions but the most effective method to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. If you're experiencing issues with this part, check for audi key fobs signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, fobs as i was accelerating off the highway paytoll at maximum speed I noticed a significant decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, three were soaked with gazoline and the fourth one was dry. When I start the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline jump out but the 4th stay closed. I checked the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I assume that the problem is elsewhere.

I also tried to reset PID without success. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I think I've ruled everything else out. But i'm worried that I might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to 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 in a local parts store. It is simple to test them by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black end of the connector). They must be infinite ohms.

4. ECU

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

A damaged G28 sensor could cause an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, and/or a misfire while in the gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these signs. They're inexpensive and easy to locate, especially when they're an Bosch model like ours. Alternatively, the GM version of this unit is also a great option.

5. Tachometer

A failing engine speed sensor could be the reason behind numerous issues in your vehicle. It is an important part of the transmission of your audi Q5 Key since it sends information to the ECU about how fast or slow the car's engine is turning. If the sensor fails, it could affect the performance of the transmission and the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is a common feature across the Audi A1 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 may find good ones in wrecking yards.