How to Replace an audi tt Key fob G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located at the edge of transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails, the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky as there are two different pins for the connector and they perform different functions but the best way to test it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is at full operation. If you're experiencing issues with this sensor, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge reduction in power. It was like the engine was running out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs. Three were drenched with gazoline the 4th one was dry. I put a piece of tissue over each injector hole, and when I start the engine without sparks, the 3 with gazoline jump right out. The 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. Therefore, i think the issue is somewhere else.

I also tried to reset the PID but with no luck. The car will start if the G28 is not plugged in and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I feel like i've pretty much eliminated everything else. But i'm worried that I might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is the same as the G4 and both function in the 80 100 200, audi key fobs key replacement key for audi a4 Cost (mariskamast.net) UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. It is simple to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft to make decisions about fuel injector timing etc. To accomplish this, it makes use of 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 failing G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or a misfire in the gear. If you experience any of these issues it is likely that your sensor is going bad and needs replacing. They're inexpensive and easy to locate, especially in the case of an Bosch sensor like ours. Alternatively, GM's version of this part is a good option.

5. Tachometer

A faulty engine speed sensor could be the cause of many issues in your vehicle. It's a crucial component of the transmission in your audi key programmer since it sends information to the ECU on how fast or slowly the car's engine is spinning. When this sensor fails, it will cause problems for the transmission as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate fuel and boost, as well as timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity from 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 see a resistance of approximately 1000 ohms between these points. This is the same across the replacement key audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU, so you might find some good ones in wrecking yards.