How to Replace an Audi Smart Key Replacement 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 message to the ECU via 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, just above the flywheel ring. This 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 signals to the G5 tachometer inside the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.

If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and Audi Keyless Entry possibly indicating the chain is stretched or a jump 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 because there are various pins on the connector, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss like the engine is out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the 4th was dry. When I start the engine with no sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stays shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. Therefore, i think the issue is elsewhere.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. 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 oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I'm not sure what to do, as i think i've pretty much ruled out everything else. However, i'm afraid that i might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or 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 on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

The signs of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when in gear. If you are experiencing any of these issues it is likely that your sensor is failing and requires replacement key for audi. They're cheap and easy to find particularly in the case of a Bosch unit like ours. Alternately, GM's version this part is an excellent choice.

5. Tachometer

A faulty engine speed sensor could be a cause for a slew of problems in your car. It's an essential component of your audi replacement key fob's transmission, since it relays information to the ECU about how fast or Audi Tt Replacement Key slow the car's crankshaft is turning. If this sensor fails, it could affect the performance of the transmission and the other car's components.

The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through a grey wire. The ECU then uses and processes the signal to control fuel, timig, and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can 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 detect an average resistance of 1000 ohms between these points. This is a standard part that is found across the audi key shell 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.