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. This sensor is situated near the transmission's edge, above the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference to correlate 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 start spark and injectors according to the situation.
If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper chain of timing. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test because there are different connector pins, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is fully functional, it should read approximately 1000 ohms. Look for signs of coolant, or oil in the connector bay if there are problems with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at a high speed, i noticed a huge reduction in power. It was like the engine had run out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was unclean. I put a piece of tissue over each hole in the injector and when i start the engine with no sparks, the 3 with gazoline jump out. The 4th one stays shut. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero ohm. I'm assuming the issue is elsewhere.
audi a1 key replacement tried to reset the PID with no success. The car will start when the G28 is unplugged and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I don't know what to do. audi a3 key replacement think I've all other possibilities out. But i'm worried that I might have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or a parts store. Test them out by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go badly, you will see codes on the diagnostic scanner that can cause the engine to shut down.
A damaged G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or a misfire in gear. If you experience any of these issues, it is likely your sensor is going bad and should be replaced. The good thing is that they are very cheap and readily available, especially in the case of the Bosch model, which is what we have. Alternatively, the GM version of this part is also a good option.
5. Tachometer
A faulty engine speed sensor could be the cause of many problems in your car. It is a crucial part of the Audi's transmission as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. If the sensor fails, it can disrupt the performance of the transmission as well as the rest of the car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU is then able to process this signal to control the flow of fuel, timig and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, 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. It should show approximately 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU, so you might find them in wrecking yards.