How to Replace an audi a1 key fob tt replacement key for audi a4 programming (her explanation) 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 transmission's edge just above the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49), then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an indicator to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors according to the situation.

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 the possibility of a chain stretch or jumped chain link in the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit tricky because there are two pins for the connector and they have different functions but the most effective method to test it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading around 1000 ohms. Check for signs of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning, 3 were soaked with gasoline and the fourth was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline pop out, but the 4th one stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID with no success. The car will start when the G28 is not plugged in and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I don't know what to do. I think I've all other possibilities out. I'm concerned that i may have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. It is easy to test them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the position and speed of the crankshaft to make a decision about fuel injector timing etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these sensors, the diagnostic scanner will show codes that could lead to the engine shutting down.

A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, or a misfire while in the gear. It is likely that the sensor is failing and needs to be replaced if you notice any of these symptoms. The good thing is that they are quite affordable and readily available, especially when you're looking at an Bosch unit like ours. Alternately, the GM version of this unit is also a great option.

5. Tachometer

A faulty engine speed sensor could be the cause of numerous problems in your car. It's an essential component of the transmission of your Audi, as it transmits information to the ECU regarding how fast or slowly the engine of the car is spinning. When this sensor fails, it will cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It sends signals via gray wire to ECU pin T55/49. The ECU then uses and processes the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is a common feature across the audi connect key 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.