How to Replace an spare audi key G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated near the edges of the transmission, above the flywheel ring gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer on 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 an uncolored wire. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC, and the location 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 message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumpy chain link in the upper chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult because there are two pins for the connector and they serve different purposes but the best way to test it is by measuring resistance between the sensor and the ECU. When the sensor is fully operational, it should read about 1000 ohms. If you’re having issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or my injectors weren’t firing. This morning i pull out the spark plugs, 3 were soaked with gazoline and the fourth one was dry. I put a piece of tissue over each injector hole and when I start the engine with no sparks, the 3 with gazoline jump out. The fourth one remains shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.
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 issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I’m not sure what to do, as i think i’ve pretty much ruled out everything else. But i’m worried that I may have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from 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 an extra in a wrecking shop or parts store. It is simple to test them – put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector’s end up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that has to know the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown.
A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts more quickly than normal, and/or a misfire in the gear. If you experience any of these issues, it is likely your sensor is deteriorating and needs replacing. The good thing is that they are very affordable and easy to find, especially when you’re looking at the Bosch model, which is what ours are. Alternately, GM’s version this component is a good option.
5. Tachometer
A faulty engine speed sensor could be a cause for a slew of problems in your car. It is a crucial part of your audi replacement key fob‘s transmission, since it relays information to the ECU about how the car’s crankshaft is turning. This sensor could cause the transmission to fail and other car key cover audi components to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU uses this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those points. This is a standard component across the Audi Key Fob Replacement Cost 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.