5 Laws That Anyone Working In Audi G28 Should Know

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 situated near the transmission's edge, above the flywheel gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via an uncolored wire. The ECU uses this information to regulate fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper timing chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult because there are two connector pins and they perform different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. If you're having issues with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced an abrupt drop in power like the engine is out of gas or injectors are not firing any more. Today, i pulled out the spark plugs, three were drenched in gazoline, the 4th one 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 remains shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is somewhere else.
lost audi keys tried to reset the PID with no success. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, i feel i have pretty much eliminated everything else. However, i'm afraid that i might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or in a local parts store. It is easy to test 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 up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that needs to know the position and speed of the crankshaft in order to make a decision about timing of the fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these goes badly, you will see codes on the diagnostic scanner that could cause engine shut down.
A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, or an unfire when in the gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They are cheap and easy-to-find especially in the case of an Bosch model like ours. Alternatively, GM's version of this part would be an option.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It's an essential component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. When this sensor fails, it could affect the performance of the transmission and the rest of the car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then processes the signal to control fuel, timig, and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find some good ones in wrecking yards.