How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located near the transmission's edge, above the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate 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 are out of sync and could indicate chain stretch or a jumped link on the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky because there are two connector pins and they serve different purposes however the best way to test it is to measure the resistance between the sensor and the ECU. If the sensor is functional, it should read around 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge drop in power. It was as if the engine had run out of gas. Or, my injectors were not firing. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When I start the engine without sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming that the issue is in another location.
I also tried to reset PID but without success. The car will start when the G28 is disconnected, but it is running advanced key audi fine with the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed here that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.
I don't know what to do. I think I've all other possibilities out. I'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sender is identical to the G4 and both function what is the audi advanced key in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. Testing them is easy - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's end). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines needs to know both the position and speed the crankshaft to determine timing of fuel injectors, etc. 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 show codes that could cause the engine shutting down.
Some of the symptoms of a failing website G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when you're in gear. If you experience any of these issues it is most likely that your sensor is failing and needs replacing. The good thing is that they are quite affordable and readily available, especially in the case of an Bosch model, which is what ours are. Alternately, GM's version this part would be an option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of problems in your vehicle. It's a vital component of the Audi's transmission as it sends here information to the ECU about how fast or slow the car's crankshaft is turning. This sensor could cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU uses this signal to control fuel and boost, and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test 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 on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these points. This is a standard component across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.