10 Untrue Answers To Common Audi G28 Questions Do You Know The Correct Answers?
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission, above the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through a grey wire. what to do if you lose your audi key G28 Car Keys utilizes this information to control the amount of fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. 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 since there are several pins on the connector, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is functional, it should read around 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is running out of gas or injectors are not firing at all. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. When i crank the engine, there are no sparks i put tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. I think the issue is somewhere else.
I also tried to reset PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c, even if I unplug it. 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 certain what to do, i believe that i've completely ruled out all other possibilities. I'm concerned that i may have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is the same as 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. It is easy to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must be aware of the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.
Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter and gears that shift faster than normal and/or a misfire when you are in gear. It is probable that your sensor is failing and needs to be replaced if you experience any of these signs. They are cheap and easy-to-find, especially if they're a Bosch model like ours. If you prefer, GM's version of this part would be an excellent choice.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of issues in your vehicle. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed sensor is located at the edge of the transmission, above the flywheel ring gear and sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU is then able to process this signal to control the flow of fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can check continuity between pin 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. You should see the resistance to be around 1000 ohms in these areas. This is a typical part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.