How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you 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 to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors accordingly.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and could indicate the chain is stretched or a jump link on the upper chain of timing. The code won't appear 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 most effective way to test it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading approximately 1000 ohms. Look for signs of coolant or oil in the connector bay if there are issues with this part.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant drop in power. It was like the engine was running out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs, 3 were soaked with gazoline and the 4th one was dry. I placed a tissue over each injector hole, and when I turn the engine on without sparks, the three that have gazoline pop right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming the issue is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However, the intermittent misfire problem 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 oil pressure gauge 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 think i've pretty much ruled out everything else. But i am afraid I might have missed something. If anyone has any suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking here shop or a parts store. It is simple to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes badly, you will see codes on the diagnostic scanner which can cause the engine to shut down.
Some of the symptoms of a failing G28 sensor are an inaccurate gearbox rev counter and gears that shift faster than normal and/or misfiring when you are read more in gear. It is likely that the sensor is failing and needs to be replaced read more if you notice any of these symptoms. They're cheap and easy to find, especially in the case of a Bosch sensor like ours. Alternately, GM's version this part would be an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of numerous issues 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 turning. This sensor could cause the transmission to malfunction and other components in the car to be affected.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends website a signal via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity from the website sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a standard part that is found 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.