How to Replace an audi connect key G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission over the flywheel gear. It transmits a signal the ECU via the 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, above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors according to the situation.

If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain is stretched or a jump link on the upper timing chain. The code won’t appear without the additional information provided by other sensors (G4 or G40).

It’s a bit tricky to test since there are several pins on the connector, and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is in full operation. If you’re having issues with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed, i noticed a huge decrease 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 with gasoline and the 4th was dry. I put tissue over each injector hole and when i start the engine with no sparks, the ones that have gazoline pop right out. The 4th one stays shut. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero Ohm. So i assume the problem is elsewhere.

I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil pressure gauge 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 think I’ve ruled everything else out. But i am afraid I might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sender is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. Test them out – put 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 side). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines must know both the speed and Audikey position of the crankshaft to make decisions regarding timing of fuel injectors, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

Some of the symptoms of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or misfiring when in gear. If you experience any of these problems, it is likely that your sensor is failing and should be replaced. They’re inexpensive and easy to locate especially in the case of an Bosch unit like ours. Alternately, the GM version of this component is also a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues in your audi car key replacement cost. It’s a crucial component of the transmission in your audi a1 key fob, as it transmits information to the ECU about how fast or slowly the car’s engine is spinning. This sensor can cause the transmission to fail and other car components to be affected.

The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU then processes the signal to control fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should observe approximately 1000 ohms resistance between those two pins. This is a typical part that is found across the replacement audi car key 80 100, 200, UrS and Audi key programming (https://gm6699.com/home.php?mod=Space&uid=3551067) RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.