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 situated at the edge of transmission, above the flywheel gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor serves 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 so it can trigger spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit challenging because there are two connector pins, and they have different functions however the best way to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is in full operation. Examine for signs of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge reduction in power. It was like the engine was running out of gas. Or my injectors were not firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. When i crank the engine with no sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I assume that the problem is somewhere else.
I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not certain what to do, as i think i've pretty much ruled out everything else. I'm worried that i might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by 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. It is easy to find the spare in a salvage shop or parts store. It is simple to test them by putting your DMM here in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, for example. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you spare audi key cost have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger the engine shutting down.
A damaged G28 sensor could result in an inaccurate speed counter for the more info gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. It is likely that the sensor get more info is failing and requires to be replaced if you encounter any of these signs. The good thing is that they are quite affordable and easily accessible, especially when you're looking at a Bosch unit like ours. Alternatively, the GM version of this part is also a good option.
5. Tachometer
A faulty engine speed sensor could be the reason behind a slew of issues in your car. It's an essential component of the Audi's transmission as it sends information to the ECU about how fast or slow the car's crankshaft is rotating. If get more info the sensor fails, it could disrupt the performance of 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 transmits a signal via gray wire to ECU pin T55/49. The ECU is then able to process the signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, 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 detect 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. Good ones might be availble in wrecking yards.