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. The sensor is located near the edges of the transmission just above the flywheel ring gear. It sends a message to the ECU via 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 an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU uses this information to control 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 must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).
It can be a bit difficult to test as there are various 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. If the sensor is operational, it should be reading about 1000 ohms. If you're having issues with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the 4th was dry. When i crank the engine, there are no sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline pop out, but the 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I assume that the problem 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 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.
I'm not sure what to do, i believe that i've completely ruled out all other possibilities. However, i'm afraid that i might have missed something. Let me know If 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 function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or from a parts store. It is easy to test them: simply switch your DMM into resistance mode and determine 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) click here engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger the engine shutting down.
A damaged G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, or a misfire in the gear. If you are experiencing any of these issues, it is most likely that your sensor is going bad and needs replacing. The good news is they are very cheap and easy read more to find, especially if you're looking at a Bosch unit like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues with your vehicle. It's an essential component of the Audi's transmission as it new audi car key sends information here to the ECU about how the car's crankshaft is turning. If the sensor fails, it could affect the performance of the transmission and the rest of the car's components.
The G5 engine speed sensor is located on the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU car key replacement audi at pin T55/49, via a grey wire. The ECU then 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 determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, 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 and pin T26a/12. You should see approximately 1000 ohms of resistance between those two pins. This is a standard part across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.