20 Myths About Audi G28: Dispelled
20 Myths About Audi G28: Dispelled
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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. This sensor is located near the transmission's edge just above the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49) and then to the tachometer within 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 an electrical signal to ECU pin T55/49 via a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.
If this sensor fails to function, the ECU will display an error code P00160. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test because there are several connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should read approximately 1000 ohms. Check for signs 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 like the engine is running out of gas or injectors are not firing any more. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the fourth was dry. When I crank the engine without sparks i put tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stay closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming the issue is in another place.
I also tried to reset the PID without success. The car will start when the G28 is disconnected and is running fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit audi spare key replacement is showing 2 replacement audi car key bar when the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i think i've pretty much eliminated everything else. However, i'm afraid that I may have missed something. If anyone has any ideas please let me know! TIA!
3. Fuel Pump
The fuel pump of the g28 gets more info a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. Testing them is easy by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) click here engines must know the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger the engine shutting down.
A damaged G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, or a misfire while in gear. If you have any of these issues it is likely that your sensor is failing and requires replacement. The good news is that they are quite affordable and readily available, especially in the case of the Bosch unit which is what ours are. Alternatively, the GM version of this unit is also a good option.
5. Tachometer
A failing engine speed sensor could be the cause of many issues with your car. It's a crucial component of the transmission of your Audi because it relays information to the ECU on how fast or slow the engine of the car is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49 through an uncolored wire. The ECU then processes this signal to control fuel, timig, and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can check here test for sensor failure by checking continuity from the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should observe approximately 1000 ohms of resistance between these two points. This is a standard component across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.