How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 using a grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC, and the location of the camshaft in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit tricky since there are two connector pins and they have different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading about 1000 ohms. Look for evidence of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday accelerating full speed from highway paytoll, I experienced massive power loss as if the engine was running out of gas or the injectors aren't firing anymore. Today, i pulled out the spark plugs. Three were drenched in gazoline, the 4th one was dry. I put tissue over each hole in the injector and when i start the engine without sparks, the three with gazoline jump right out. The fourth one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found 0ohm. So i assume the problem is somewhere else.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. click through the next document noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, as i feel i have pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by 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 parts store. It is easy to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to know the position and speed the crankshaft in order to make a decision about timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go badly, you will see codes on the diagnostic scanner which can cause the engine to shut down.
A failing G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, and/or a misfire in the gear. It is probable that the sensor is failing and requires to be replaced if you notice any of these signs. The good news is that they are very cheap and readily available particularly if you're looking at the Bosch unit like ours. Alternatively, the GM version of this component is also a good choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It is an important part of the transmission in your Audi since it sends information to the ECU on how fast or slow the car's engine is turning. If this sensor fails, it could disrupt the performance of the transmission as well as the rest of the car's components.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes this signal to control fuel, timig, and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, 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 as well as pin T26a/12. You should detect the resistance to be around 1000 ohms between these points. This is a typical part across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.