7 Small Changes That Will Make The Biggest Difference In Your Audi G28

How to Replace an audi q7 replacement key G28 Engine Speed Sensor

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

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors according to the situation.

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

Testing is a bit tricky since there are two pins for the connector and they serve different purposes however the best method to test it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should be reading around 1000 ohms. Check for evidence of coolant or Audi key replacement oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed, i noticed a huge reduction in power. It was as if the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, three were drenched in gazoline, the fourth one was dry. I put tissue over each injector hole and Audikey (Jisuzm.Tv) when I turn the engine on without sparks, the 3 with gazoline jump out. The 4th one remains closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is in another place.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit shows 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 eliminated everything else. But i'm worried that I may have missed something. If anyone has 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 sensor 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 wrecking yard or in a local 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 end). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed of the crankshaft in order to make a decision about timing of fuel injectors, etc. It uses 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 show codes that could cause an engine shutdown.

The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when in gear. If you have any of these problems, it is most likely that your sensor is going bad and should be replaced. The good news is they are very cheap and readily available particularly when you're looking at a Bosch unit like ours. If you prefer, GM's version of this part would be an option.

5. Tachometer

A failing engine sensor could cause a myriad of issues in your vehicle. It's a vital component of the audi car key's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is rotating. When this sensor fails, it can cause problems for the transmission and the other car's components.

The G5 engine speed sensor is situated on the outside 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 utilizes this signal to regulate fuel and boost, and also timig. It also relays it to the G5 Tachometer in instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can examine the continuity between pins 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 detect a resistance of approximately 1000 ohms in these areas. This is a common part across the new audi key 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.