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How to Replace an audi tt key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located near the transmission's edge just above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to regulate boost and fuel. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and the location of the camshaft in order to activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 code 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 chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging since there are two pins for the connector audi a1 key (click through the up coming page) and they have different functions but the best method of testing it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. Look 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 maximum speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or, my injectors were not firing. I took out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. I placed a tissue over each injector hole, and when I start the engine with no sparks, the three with gazoline jump right out. The 4th one stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I think the issue is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.

I'm not certain what to do, i believe that i've ruled out everything else. But i'm worried that i might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. Testing them is easy to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the speed and position of the crankshaft to determine timing of the fuel injector, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.

A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter or a gearbox that shifts faster than normal, or a misfire while in the gear. It is possible that the sensor is failing and needs to be replaced if you encounter any of these signs. The good news is they are very affordable and readily available, especially in the case of the Bosch sensor, which is what we have. Alternately, the GM version of this unit is also a great option.

5. Tachometer

A faulty engine speed sensor could be the cause of a slew of problems in your car. It's a crucial component of the transmission of your audi key fob because it relays information to the ECU regarding how fast or slow the engine is turning. If this sensor fails, it can disrupt the performance of the transmission as well as the rest of the car's components.

The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then processes this signal to regulate the flow of fuel, timig and audi car key replacement boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between those points. This is the same across the Audi Tt Key Case 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du So, you may find them in wrecking yards.