How to Replace an audi car keys G28 Engine Speed Sensor
In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located near by the transmission’s edge, above the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer within the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper timing chain. The code won’t appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test because there are different connector pins, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is fully operational, it should read approximately 1000 ohms. If you’re experiencing issues with this part, check for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or, my injectors weren’t firing. In the morning, i removed the spark plugs. Three were drenched with gazoline the 4th one was dry. When i crank the engine, there are no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stay closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I assume that the problem is in another location.
I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value that is -49c even after unplugging it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 when i rev the engine.
I’m not sure what to do. I believe that I’ve ruled everything else out. I’m afraid i may have missed something. If anyone has any suggestions, please let audi replacement key service near me know! 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 both function in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. It is simple to test them: simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make decisions about timing of the fuel injector, for example. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display codes that could lead to the engine shutting down.
The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox the gears are shifting faster than normal, and/or a misfire when in gear. If you have any of these issues, it is likely that your sensor is going bad and needs replacing. They’re inexpensive and easy to locate particularly in the case of a Bosch sensor like ours. Alternatively, the GM version of this part is also a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind numerous problems in your car. It’s an essential component of your replacement audi key‘s transmission, because it communicates to the ECU about how fast or slow the car’s crankshaft is spinning. If the sensor fails, it could cause problems for the transmission and 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 sends a signal via a gray wire to the ECU pin T55/49. The ECU then processes this signal to regulate fuel, timig, and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those two pins. This is a common part across the audi car keys 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.