How to Replace an audi key shell G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located near the edges of the transmission, above the flywheel ring gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated 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 then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.

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

If this sensor fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper timing chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult because there are two connector pins, and they serve different purposes however the best method to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when it is in full operation. Check for signs of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday accelerating full speed from highway paytoll, I experienced an abrupt drop in power like the engine is running out of gas or injectors are not firing at all. I took out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. I put a piece of tissue over each hole in the injector and when I start the engine with no sparks, the ones with gazoline jump right out. The 4th one remains shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I think the issue is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

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

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. Test them out by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines needs to be aware of the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.

The signs of a failing G28 sensor are an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or misfiring when in gear. If you have any of these problems, it is likely your sensor is going bad and requires replacement. The good news is that they are very affordable and easily accessible, especially when you're looking at the Bosch model, which is what we have. Alternatively, the GM version of this unit is also a good option.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues in your vehicle. It's an essential component of your audi car key case's transmission, because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. When this sensor fails, it can affect the performance of the transmission as well as the rest of the car key replacement audi's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also transmits 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 ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a standard part across the audi a4 replacement key 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.