How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via the grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using a grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used as a reference point 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 activate spark and injectors accordingly.
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 chain stretch or a jumped link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky as there are two different pins for the connector and they perform different functions but the best method of testing it is by measuring resistance between the sensor and the ECU. When the sensor is functional, it should read around 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is out of gas or injectors are not firing at all. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When I start the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th one stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not sure website what to do. I feel like i've pretty much eliminated everything else. However, i'm afraid that I might have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style sensor 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 from a parts store. Test them out - put 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 end of the connector). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.
A failing G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, or an unfire when in gear. If you experience any of these problems, it is likely that your sensor is deteriorating and needs replacing. The good thing is that they are very cheap and easy to find, especially in the case of the Bosch model, which is what ours are. Alternatively, the GM version of this part is also a good choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It is an important part of the transmission of your Audi since it sends information to the ECU about how fast more info or slowly the car's engine is turning. 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 edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin click here T55/49 via an uncolored wire. The ECU then uses and processes the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the replacement car key audi continuity between pins 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 observe around 1000 ohms of resistance between those two pins. This is a typical part 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 click here available in wrecking yards.