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 situated near the edges of the transmission just above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends an indicator to the G5 Tachometer within the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft reached TDC and also the position of the camshaft, to trigger the spark and injectors.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of 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).
audi a3 key replacement can be a bit difficult to test as there are various connector pins, 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 fully 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 accelerating from highway paytoll at a high speed I noticed a significant reduction in power. It was like the engine had run out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs, 3 were soaked with gazoline and the 4th one was dry. I placed a tissue over each injector hole and when i start the engine with no sparks, the 3 with gazoline jump right out. The 4th one stays closed. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero ohm. So i assume the problem is in another place.
I also tried to reset PID but without success. The car can start when the G28 is disconnected and runs fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I don't know what to do. I feel like i've pretty much eliminated everything else. I'm worried that i might have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. It is simple to test them by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). audi a1 key replacement must be infinite ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines must be aware of the speed and position of the crankshaft in order to make a decision about fuel injector timing, etc. It utilizes 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 could cause engine shut down.
Some of the signs of a failing G28 sensor include an inaccurate rev counter in the gearbox and gears that shift faster than normal and/or a misfire when you're in gear. If you experience any of these problems, it is likely that your sensor is going bad and should be replaced. The good thing is that they are quite affordable and readily available, especially if you're looking at a Bosch model, like ours. Alternatively, audi a1 keys of this unit is also a good choice.
5. Tachometer
A faulty engine speed sensor could be the reason behind numerous issues in your car. It's an essential component of the transmission in your Audi because it relays information to the ECU on how fast or slowly the engine of the car is turning. When this sensor fails, it could cause problems for the transmission, as well as the rest of the car's components.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to control fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins 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. There should be an average resistance of 1000 ohms between these two points. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.