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

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It sends a signal to the ECU via an uncolored wire (T55/49) and then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, just above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and where the camshaft lies so that it can activate the spark and injectors.

If this sensor fails, the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).

It's a bit tricky to test since there are various connector pins, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is operating at its maximum. If you're experiencing issues with this component, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a significant drop in power. It was like the engine had run out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs, three were drenched with gazoline the fourth was dry. When I crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th one stays closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found 0ohm. I assume that the problem is elsewhere.

I also tried to reset PID but without success. The car can start if the G28 is not plugged in and runs fine when it is plugged in, but still has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.

I'm not sure what to do. I believe that I've all other possibilities out. But i'm worried that I may have missed something. If anyone has any suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals 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 junkyard or from a parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

The signs of a failing G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when in gear. If you are experiencing any of these problems, it is likely that your sensor is going bad and should be replaced. The good thing is that they are very affordable and easy to find, especially when you're looking at an Bosch model, like ours. Alternately, GM's version this component is an excellent choice.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of many issues in your car. It's an essential component of your audi remote key's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. If the sensor fails, it could affect the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then processes the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. There should be a resistance of approximately 1000 ohms in these areas. This is the same across the audi keyless entry a5 key fob [imoodle.Win] 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 Du You may also find good ones in wrecking yards.