How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located at the top of the transmission above the flywheel ring 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
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 through the grey wire. The ECU uses this information to control boost and fuel. It also sends signals 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 needs to know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain of timing. However, the code won't appear on its own, without additional information from other sensors (G4 and G40).
It is a little tricky to test as there are different pins on the connector and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When audi a1 car key is operational, it should be reading approximately 1000 ohms. If you are having problems with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced massive power loss like the engine is out of gas or the injectors aren't firing anymore. audi a1 key took out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. I put tissue over each injector hole, and when i start the engine with no sparks, the three that have gazoline pop right out. The 4th one remains shut. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. I'm assuming the issue is in another place.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. Also i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, i think i've pretty much eliminated everything else. I'm afraid i may have missed something. Let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft to determine timing of the fuel injector, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.
A malfunctioning G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or a misfire in gear. It is likely that the sensor is failing and requires to be replaced if you notice any of these signs. They're cheap and easy to find, especially when they're a Bosch unit like ours. You can also choose the GM version of this unit is also a great option.
5. no title could be a cause for many problems in your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU on how fast or slowly the car's engine is spinning. This sensor could cause the transmission to fail 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 transmits signals via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a standard component 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 parts could be found in wrecking yards.