How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via a grey wire. The ECU uses this information to control fuel and boost. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors in the right way.
If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of sync 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 be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging since there are two connector pins, and they serve different purposes but the most effective method to test it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. Examine for evidence of coolant or oil in the connector bay if you are experiencing issues with this component.
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 the injectors are not firing any more. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. I placed a tissue over each injector hole and when I turn the engine on without sparks, the 3 with gazoline jump out. The fourth one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I think the issue is elsewhere.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.
I'm not sure what to do. I feel like i've pretty much eliminated everything else. I'm worried that i might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and both check here are used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. It is simple to test here them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor more info G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could cause the engine shutting down.
A damaged G28 sensor could cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or a misfire while in the gear. If you experience any of these problems, it is most likely that your sensor is failing and should be replaced. They're inexpensive and easy to locate, especially when they're a Bosch unit like ours. You can also choose the GM version of this part is also a good choice.
5. Tachometer
A spare audi key cost malfunctioning engine sensor can cause a variety of issues in your vehicle. It is a crucial part of the Audi's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. read more It sends a signal via an uncolored wire to the ECU pin T55/49. 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 located in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. It should show approximately 1000 ohms of resistance between those two pins. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find good ones in wrecking yards.