How to Replace an audi a3 key G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through an uncolored wire. The ECU uses this information to regulate fuel and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also where the camshaft lies so that it can activate the spark and injectors.

If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).

Testing can be a bit difficult as there are two different connector pins, and they serve different purposes but the most effective way to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when the sensor is operating at its maximum. If you are having problems with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed, i noticed a huge drop in power. It was like the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs. Three were soaked with gazoline and the 4th one was dry. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the ones that have gazoline pop right out. The fourth one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. I assume that the problem is in another location.

I also tried to reset PID but without success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. 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. I feel like i've pretty much ruled everything else out. But i'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 gets 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 so you can easily find one at a salvage yard or from a parts store. It is simple to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injector, for example. 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 could cause engine shut down.

A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire while in gear. If you are experiencing any of these problems, it is likely that your sensor is failing and needs replacing. The good news is they are very affordable and readily available particularly if you're looking at an Bosch sensor, which is what we have. Alternatively, GM's version of this part would be an option.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of numerous issues in your car. It's a vital component of the audi car key case's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. If this sensor fails, it could disrupt the performance of the transmission as well as the other car's components.

The G5 engine speed sensor is located on the outside of the transmission just 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 control the amount of fuel and boost, and also timig. It also relays it 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 [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those points. This is a common component across the audi tt key replacement tt key fob (https://king-wifi.win/Wiki/Weinsteinevans8771) 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.