How to Replace an audi a4 replacement key G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located on the edge of the transmission just above the flywheel ring 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 at the edges of the transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to control boost and fuel. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.

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

It's a bit tricky to test as there are different pins on the connector and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is at full operation. If you're having issues with this sensor, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive drop in power. It was like the engine was running out of gas. Or, my injectors weren't firing. This morning i pull out the spark plugs. Three were drenched with gazoline the 4th one was dry. I placed a tissue over each injector hole and when I turn the engine on without sparks, audi key fob the three with gazoline jump out. The 4th one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming the issue is in another place.

I also tried to reset the PID with no success. The car will start if the G28 is disconnected and is running fine when it is plugged in but it still has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm audi key fob not working sure what to do. I believe that I've eliminated everything else. But i'm worried that I might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style sender 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 wrecking yard or at a parts store. It is simple to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will display the codes that could trigger an engine shut down.

The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when in gear. If you experience any of these issues it is most likely that your sensor is going bad and should be replaced. The good thing is that they are very cheap and easily accessible particularly if you're looking at an Bosch model, which is what ours are. You can also choose the GM version of this component is also a good choice.

5. Tachometer

A failing engine speed sensor could be the reason behind numerous issues in your vehicle. It's a crucial component of the transmission of your Audi Q7 Replacement Key since it sends information to the ECU regarding how fast or slowly the engine is spinning. If this sensor fails, it will disrupt the performance of the transmission, as well as the other car's components.

The G5 engine speed sensor is situated 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 then uses and processes the signal to control the flow of fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This is a common component across the audi spare key 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.