How to Replace an audi car key cover G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates 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 message to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via the grey wire. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 tachometer in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors accordingly.
If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and repairing Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins, and they serve different purposes but the most effective method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. Check for signs of coolant or oil in the connector bay if you are experiencing issues with this component.
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 injectors are not firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. When i crank the engine without sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline pop out, but the 4th stays shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found 0ohm. I think the issue is somewhere else.
I also tried to reset the PID but without success. The car is able to start when the G28 is not plugged in and is running fine when it is connected however it has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do. I think I've all other possibilities out. But i'm worried that I may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent by the RPM sensor. The GM-style transmitter is similar 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 a parts store. It is simple to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.
A failing G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, or a misfire while in the gear. It is possible that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is they are quite affordable and easily accessible, especially if you're looking at a Bosch sensor, like ours. Alternatively, the GM version of this part is also a good choice.
5. Tachometer
A failing engine sensor could cause a variety of issues within your vehicle. It's a crucial component of the transmission in your Audi Car Key Replacement Cost because it relays information to the ECU about how fast or slow the car's engine is spinning. If the sensor fails, it could disrupt the performance of the transmission as well as the other car's components.
The G5 engine speed sensor is located at the edge of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to control the flow of fuel and boost and also timig. It also relays it to the G5 Tachometer in 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 via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between these two points. This is a standard part across the audi q5 key 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.