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. This sensor is located at the edge of transmission, above the flywheel gear. It sends a message to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer located 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 trigger spark and injectors according to the situation.
If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult because there are two connector pins, and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. Check for signs of coolant, or oil in the connector bay if you have issues with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll i had an abrupt drop in power like the engine is out of gas or injectors aren't firing anymore. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. When I start the engine with 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 one stays closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID without success. The car can start when the G28 is disconnected and is running fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not certain what to do, but i feel i have pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. Let me know should you have any suggestions! TIA!
3. how to get a new audi key of the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. It is simple to test them by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make a decision about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.
A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts more quickly than normal, and/or an unfire when in gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these signs. The good news is they are very affordable and easily accessible particularly if you're looking at a Bosch unit which is what we have. Alternately, the GM version of this part is also a good option.
5. Tachometer
A faulty engine speed sensor could be the cause of a slew of issues in your car. It's an essential component of the transmission in your Audi since it sends information to the ECU on how fast or slowly the engine of the car is turning. This sensor can cause the transmission to malfunction 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 sends signals via a gray wire to the ECU pin T55/49. The ECU then processes the signal to control fuel, timig, and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can test 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 via pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms between these two points. This is the same 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 them in wrecking yards.