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How to Replace an audi keyfob G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located at the top of the transmission above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to control boost and fuel. It also sends an indicator to the G5 Tachometer located in 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 start spark and injectors accordingly.

If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jump in the chain link of the upper chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit tricky as there are two different connector pins, 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 approximately 1000 ohms if the sensor is operating at its maximum. If you're having issues with this part, check for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power as if the engine was running out of gas or the injectors are not firing at all. I took out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. When I crank the engine without sparks i put tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming that the issue is somewhere else.

I also tried to reset the PID without success. The car is able to start if the G28 is not plugged in and runs fine when it is connected however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I don't know what to do. I think I've ruled everything else out. I'm concerned that i may have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80, 100, 200, 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 - simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite ohms.

4. ECU

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

The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when you are in gear. If you are experiencing any of these issues, it is most likely that your sensor is failing and needs replacing. The good news is they are quite affordable and easily accessible particularly if you're looking at the Bosch sensor, which is what ours are. Alternately, the GM version of this unit is also a good choice.

5. Tachometer

A failing engine speed sensor could be the cause of numerous issues with your car. It's a vital component of your audi key blade's transmission, because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. This sensor can cause the transmission to fail and other components in the car to be affected.

The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost, and also sends it on to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. You should see an average resistance of 1000 ohms between these two points. This is the same across the audi a5 key fob q5 programming audi key (just click the up coming internet page) 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du, so you might find good ones in wrecking yards.