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How to Replace an audi tt key G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated near the edges of the transmission, above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU uses this information to control fuel and boost. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used to connect with 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 throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging as there are two different connector pins, and repairer they have different functions but the most effective method to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should read approximately 1000 ohms. If you are having problems with this sensor, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power like the engine is running out of gas or the injectors are not firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was unclean. When I crank the engine, there are no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline leap out, however the 4th stay closed. I tested the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. Therefore, i think the issue is somewhere else.

I also tried to reset the PID but with no luck. The car can start if the G28 is disconnected and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is zero.

I don't know what to do. I feel like i've pretty much all other possibilities out. But i am afraid i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sensor 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 junkyard or from a parts store. Testing them is easy - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that needs to be aware of the speed and position of the crankshaft to make a decision about fuel injector timing etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner which can lead to engine shutdown.

The signs of a failed G28 sensor are an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or misfiring when you are in gear. If you have any of these issues it is likely that your sensor is going bad and needs replacing. The good news is they are very affordable and readily available, especially if you're looking at the Bosch model, like ours. Alternatively, GM's version of this part would be a good option.

5. Tachometer

A faulty engine speed sensor could be the reason behind a slew of issues in your vehicle. It's an essential component of your audi connect key's transmission, because it communicates to the ECU about how the car's crankshaft is turning. When this sensor fails, it can affect the performance of the transmission, as well as the other car's components.

The G5 engine speed sensor is located on the outside 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 this signal to control the flow of fuel, audi spare Key replacement timig and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and Audi Car Key between T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This is a common feature across the audi a3 replacement key 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du So, you may find good ones in wrecking yards.