How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of 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 won't show without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging because there are two connector pins, and they perform different functions but the best method to test it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is operating at its maximum. If you are having problems with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. When I crank the engine without sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. Therefore, i think the issue is somewhere else.
I also tried to reset get more info PID but without success. The car will start if the G28 is not plugged in and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures 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 don't know what to do. I think I've eliminated everything else. However, i'm afraid that I may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel here Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on website the connector's end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must know both the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.
A damaged G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, or an unfire when in gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these symptoms. They're cheap and easy to find especially when they're an Bosch sensor like ours. If you prefer, GM's version of this part would be an excellent choice.
5. Tachometer
A damaged engine sensor could cause a number of problems in your car. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is rotating. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is website located on the outside of the transmission above the flywheel ring gear. It transmits a car key replacement audi signal to the ECU at pin T55/49, via a grey wire. The ECU then processes this signal to regulate fuel, timig, and boost, and also transmitting it 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 ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between these two points. This is a standard component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.