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 edge of transmission over the flywheel gear. It transmits 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
It is located on the outside of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC and also the position of the camshaft, to trigger the spark and injectors.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or 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 can be a bit difficult to test because there are different pins on the connector, 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 about 1000 ohms when it is operating at its maximum. Examine for signs of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is out of gas or the injectors are not firing any more. This morning i pull out the spark plugs. Three were drenched in gazoline, the fourth was dry. I placed a tissue over each hole in the injector and when i turn the engine on without sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I think the issue is somewhere else.
I also tried to reset the PID but with no luck. The car can start if the G28 is unplugged and runs fine when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when it is unplugged, shows a temperature of -49c. Also audi convenience key noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I believe that I've all other possibilities out. However, i'm afraid that I might have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate the spare in a salvage shop or a parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make a decision about timing of the fuel injectors, etc. It uses 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 can lead to engine shutdown.
A failing G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, or a misfire while in gear. If you have any of these issues, it is likely that your sensor is going bad and requires replacement. The good news is that they are very cheap and easy to find particularly when you're looking at an Bosch sensor, like ours. Alternatively, the GM version of this component is also a great option.
5. Tachometer
A faulty engine speed sensor could be the reason behind many problems in your car. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. When this sensor fails, it will cause problems for the transmission as well as the other car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Also, you can check 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 observe approximately 1000 ohms resistance between those points. audi advanced key is a standard part across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.