How to Replace an audi q7 key G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace audi key fob the G28 engine speed sensor. This sensor is located on the edge of the transmission above the flywheel ring gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the outside of the transmission, directly above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC, and the location of the camshaft so that it can activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating 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).

Testing is a bit tricky since there are two connector pins, and they have different functions however the best method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should read about 1000 ohms. If you are having problems with this sensor, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is out of gas or injectors are not firing at all. In the morning, i removed the spark plugs, 3 were drenched with gazoline the fourth was dry. I placed a tissue over each hole in the injector replacement key audi key fob not working (g2880503.izrablog.com) and when i start the engine without sparks, the ones with gazoline jump out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is in another place.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar when 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 any ideas please chime in! TIA!

3. Fuel Pump

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

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position 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 either of these sensors go wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.

A malfunctioning G28 sensor could cause an inaccurate gearbox speed counter or a gearbox that shifts faster than normal, and/or an unfire when in the gear. It is likely that your sensor is failing and needs to be replaced if you notice any of these signs. They are cheap and easy-to-find particularly when they're an Bosch sensor like ours. Alternatively, GM's version of this part would be an excellent choice.

5. Tachometer

A failing engine sensor could cause a myriad of issues within your vehicle. It's a vital component of your audi keys replacement cost's transmission, since it relays information to the ECU about how the car's crankshaft is spinning. If this sensor fails, it can cause problems for the transmission, as well as the other car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU then processes this signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between those points. This is a common feature across the audi replacement 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 them in wrecking yards.