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. The sensor is located near the edges of the transmission above the flywheel ring gear. It transmits a signal the ECU via the grey wire (T55/49) and then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate boost and fuel. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also where the camshaft lies in order to activate the spark and injectors.
If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).
It is a little tricky to test as there are different connector pins, and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is in full operation. If you're having issues with this part, check for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss like the engine is running out of gas or the injectors aren't firing anymore. This morning i pull out the spark plugs, 3 were drenched with gazoline the fourth was dry. I placed a tissue over each injector hole, and when i start the engine with no sparks, the ones with gazoline jump out. The fourth one remains closed. I checked the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I'm assuming the issue is elsewhere.
audi key fob replacement The Keylab tried to reset the PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c even when i unplug it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, i think i've pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. If anyone has any suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from 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. It is easy to find the spare in a salvage shop or parts store. Test them out by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these, the diagnostic scanner will display codes that could lead to an engine shut down.
A damaged G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, or an unfire when in the gear. If you are experiencing any of these problems, it is most likely that your sensor is going bad and requires replacement. They're inexpensive and easy to locate particularly if they're a Bosch sensor like ours. If you prefer, GM's version of this component is a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of problems in your car. It is a crucial part of the Audi's transmission as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This part is common 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 good ones in wrecking yards.