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

Charles the Humble Technician shows you how to replace audi key fob the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge, 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 sensor is located at the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using an uncolored wire. The ECU utilizes this information to control boost and fuel. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.

If this sensor fails, the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit challenging because there are two pins for the connector and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced an abrupt drop in power like the engine is out of gas or the injectors are not firing at all. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. When I start the engine without sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th one stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.

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

I'm not sure what to do, as i believe that i've eliminated everything else. But i'm worried that i might have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's 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 must know the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go badly, you will see codes on the diagnostic scanner which can lead to engine shutdown.

A malfunctioning G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or a misfire while in the gear. If you have any of these problems, it is most likely that your sensor is failing and needs replacing. The good news is they are quite affordable and readily available, especially when you're looking at an Bosch model, which is what ours are. Alternatively, GM's version of this component is an excellent choice.

5. Tachometer

A failing engine speed sensor could be the cause of many issues in your vehicle. It's a vital component of your audi Remote Key's transmission, as it sends information to the ECU about how the car key cover audi's crankshaft is spinning. If the sensor fails, it can disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU then uses and processes the signal to control fuel, timig, prices and boost, and also sends it on to the G5 Tachometer located in 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 pin T6a/1 and the instrument cluster pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This is a typical part across the audi tt key programming 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.