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 near the transmission's edge just above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to control fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
It is a little tricky to test as there are various pins on the connector, and they all have different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is fully functional, it should read around 1000 ohms. Look for signs of coolant, or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power as if the engine was running out of gas or injectors are not firing anymore. Today, i pulled out the spark plugs, 3 were soaked with gazoline and the fourth one was dry. I put tissue over each injector hole, and when i start the engine with no sparks, the 3 with gazoline jump out. The 4th one remains closed. I checked the ground connection of ECU pins 14,30 and 48/55. I found zero ohm. I think the issue is in another location.
I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, as i believe that i've ruled out everything else. I'm worried that i might have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. It is simple to test them - simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the position and speed of the crankshaft to make decisions regarding timing of fuel injectors, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you website encounter a problem with either one of these, the diagnostic scanner will show codes that could lead to the engine shutting down.
Some of the signs of a failed G28 sensor are an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or misfiring when you're in gear. If you have any of these issues it is likely your sensor is going bad and needs replacing. They're inexpensive and easy to locate especially when they're a Bosch unit like ours. Alternatively, GM's version of this part is a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind check here numerous issues with your car. It's a crucial component of the transmission in your Audi, read more as it transmits information to the ECU on how fast or slow the car's engine is spinning. This sensor can cause the transmission to fail and other components in the car to be affected.
The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear and transmits a signal website to the ECU at pin T55/49, via a grey wire. The ECU then processes this signal to control fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to here the tachometer. Additionally, 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 detect the resistance to be around 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 DU You may also find good ones in wrecking yards.