How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission just above the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using the grey wire. The ECU utilizes this information to control boost and fuel. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors in the right way.
If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
It can be a bit difficult to test as there are several connector pins, and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is in full operation. Check for signs of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced an abrupt drop in power as if the engine was running out of gas or injectors aren't firing any more. In the morning, i removed the spark plugs. Three were soaked with gazoline and the 4th one was dry. When I crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th one stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. Therefore, i think the issue is elsewhere.
I also tried to reset PID but without success. The car can start when the G28 is disconnected and is running fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even if it is not more info plugged in, shows temperatures of -49c. Also, i noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. I'm concerned that i may have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump read more in the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both are read more used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or in a local parts store. It is easy to test them - just put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump check here at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to be aware of the position and speed the crankshaft in order to make a decision about fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go bad you will get codes on the diagnostic scanner that could cause engine shut down.
Some of the signs of a failing read more G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you're in gear. If you have any of these problems, it is likely that your sensor is failing and should be replaced. The good news is they are very cheap and easily accessible particularly in the case of an Bosch unit like ours. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A failing engine speed sensor could be the reason behind numerous issues in your vehicle. It's an essential component of your Audi's transmission, since it relays 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 components in the car to be affected.
The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU uses this signal to regulate the flow of fuel and boost as well as timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the 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. It should show around 1000 ohms of resistance between these two points. This part is common across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 DU So, you may find them in wrecking yards.