How to Replace an audi lost key G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is situated at the top of the transmission above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors according to the situation.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain of timing. However, the code won’t be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two pins for the connector and they serve different purposes but the best method to test it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is operating at its maximum. If you are having problems with this sensor, look for signs 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 injectors are not firing at all. I took out the spark plugs this morning, replacement audi a3 key 3 were soaked with gasoline and the fourth was dry. I placed a tissue over each injector hole and when I turn the engine on without sparks, the ones with gazoline jump out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I’m assuming the issue is somewhere else.
I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However, the intermittent misfire problem still occurs 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 gauge in the cockpit shows 2 bars while the actual pressure is zero.
I’m not certain what to do, i feel i have pretty much eliminated everything else. I’m afraid i may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find the spare in a salvage shop or parts store. Test them out – put your DMM in resistance mode and measure between pins 1 (with the bump on the connector’s end up) and replacement audi Key cost uk 2 (2nd from the left on the black end of the connector). They must be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to know the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, Audi Key replacement etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or a misfire in gear. If you experience any of these issues it is likely that your sensor is deteriorating and should be replaced. They’re inexpensive and easy to locate especially when they’re a Bosch unit like ours. Alternatively, the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues in your car. It’s a vital component of the replacement audi key cost‘s transmission since it relays information to the ECU about how fast or slow the car’s crankshaft is turning. This sensor can cause the transmission to fail and other components in the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via a grey wire. The ECU is then able to process the signal to control the flow of fuel, timig and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. You can also 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 as well as pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. This is a standard part across the new audi key 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.