How to Replace an audi a5 key fob G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends an alert 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 needs to know when the crankshaft has reached TDC and also where the camshaft lies 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 indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper timing chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are various pins on the connector and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is at full operation. Check for signs of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss as if the engine was running out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the 4th was dry. When i crank the engine with no sparks, i place a tissue on the top of each of the injector holes, the 3 drenched with gazoline jump out but the 4th stay closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I get 0ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID without success. The audi car keys will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do. I think I've all other possibilities out. However, i'm afraid that I may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is easy 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 have an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions about timing of the fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either cost of audi key replacement these, the diagnostic scanner will display codes that could cause an engine shutdown.
Some of the symptoms of a failed G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal, and/or a misfire when you are in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They're inexpensive and easy to locate especially when they're a Bosch sensor like ours. Alternatively, GM's version of this part would be an option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems in your vehicle. It's an essential component of your audi key shell q5 key; https://www.hulkshare.com/,'s transmission, as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor could cause the transmission to fail and other car components to be affected.
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 then uses and processes this signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. You can also check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should observe around 1000 ohms of resistance between these two points. This is a typical part that is found across the audi q7 key 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.