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How to Replace an audi key copy G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor sends 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 in the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors in the right way.

If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky because there are two connector pins, and they serve different purposes but the best method of testing it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. Examine for signs of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive drop in power. It was like the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I placed a tissue over each injector hole and when i start the engine without sparks, the 3 with gazoline jump right out. The 4th one stays closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. So i assume the problem is in another place.

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

I'm not sure what to do. I believe that I've all other possibilities out. I'm concerned that i may have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. It is simple to test them: simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite ohms.

4. ECU

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

Some of the signs of a failing G28 sensor are an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or misfiring when you're in gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these signs. They're inexpensive and easy to locate, especially in the case of an Bosch model like ours. Alternately, GM's version this part is an option.

5. Tachometer

A failing engine speed sensor could be the reason behind many problems in your car. It's an essential component of the transmission of your audi replacement key service because it relays information to the ECU regarding how fast or key audi slow the engine is turning. This sensor could cause the transmission to fail and other components of the audi car key to be affected.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU then processes this signal to control fuel, timig, and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between these two points. This part is common across the audi spare key replacement 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU So, you may find them in wrecking yards.