How to Replace an replacement key audi G28 Engine Speed Sensor

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

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.

If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on 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 is a bit challenging as there are two different connector pins and they have different functions but the most effective way to test it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should read around 1000 ohms. Check for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, while accelerating from the highway paytoll at a high speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was dry. When i crank the engine with no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero ohm. I'm assuming that the issue is in another location.

I also tried to reset PID without success. The car is able to start if the G28 is disconnected and it runs perfectly when it is plugged in but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is 0.

I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. But i am afraid i might have missed something. If anyone has any suggestions, please share them! 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 both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector audikey; images.google.cg, programmers end up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and Audi Spare Key an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown.

The signs of a failed G28 sensor are an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you are in gear. If you experience any of these problems, it is likely that your sensor is failing and needs replacing. The good news is that they are very affordable and easily accessible particularly if you're looking at the Bosch sensor, like ours. Alternately, GM's version this part is a good option.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues within your vehicle. It's a crucial component of the transmission in your audi q7 key because it relays information to the ECU on how fast or slowly the car's engine is spinning. This sensor could cause the transmission to fail and other components in the car to be affected.

The G5 engine speed sensor is located at the edge of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU utilizes this signal to control fuel and boost, as well as timig. It also sends it to the G5 Tachometer in instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those two pins. This is a common part that is found across the audi replacement car keys 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.