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How to Replace an audi key fobs G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated near the transmission's edge just above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using a grey wire. The ECU uses this information to regulate boost and fuel. It also sends an alert to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference point 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 start spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing can be a bit difficult since there are two connector pins, and they perform different functions but the most effective method of testing it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is operating at its maximum. Examine for evidence of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant decrease in power. It was like the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were drenched with gazoline the fourth was dry. I put tissue over each injector hole, and when I start the engine with no sparks, the three with gazoline jump out. The 4th one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is not plugged in and is running fine when it is connected however it is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I think I've eliminated everything else. I'm concerned that i may have missed something. If anyone has suggestions, please let me know! 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 junkyard or in a local parts store. It is simple to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the speed and position of the crankshaft to determine timing of the fuel injector, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which could cause engine shut down.

Some of the signs of a failing G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when you're in gear. It is possible that your sensor is failing and requires to be replaced if you encounter any of these signs. The good news is they are very affordable and readily available particularly in the case of the Bosch model, which is what ours are. Alternatively, the GM version of this component is also a good option.

5. Tachometer

A damaged engine sensor could cause a number of problems in your vehicle. It's a crucial component of the transmission in your audi key fob not working key fob replacement cost (visit these guys) since it sends information to the ECU regarding how fast or slowly the car's engine is spinning. If this sensor fails, it could disrupt the performance of the transmission as well as the other car's components.

The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via a grey wire. The ECU is then able to process this signal to control fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those points. This is a common feature across the audi replacement key service 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.