How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal 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 at the edges of the transmission, above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to control the amount of fuel and boost. It also sends a signal 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 be aware of when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.
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 indicate the possibility of a chain stretch or 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).
Testing is a bit challenging as there are two different pins for the connector and they have different functions however the best method to test it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full 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 4th was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each of the injector holes, the 3 drenched with gazoline leap out, however the 4th stay shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. Therefore, i think 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 unplugged, and it works fine when the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. audi car key replacement G28 Car Keys noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not certain what to do, i believe that i've ruled out everything else. I'm concerned that i may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal 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. You can easily locate the spare in a salvage shop or a parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines needs to know the position and speed of the crankshaft to determine timing of the fuel injector, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner which could cause engine shut down.
Some of the signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when you're in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these symptoms. They're cheap and easy to find especially in the case of a Bosch sensor like ours. You can also choose the GM version of this component is also a good choice.
5. Tachometer
A damaged engine sensor could cause a variety of issues in your car. It is an important part of the transmission of your Audi because it relays information to the ECU about how fast or slowly the engine is turning. If this sensor fails, it could affect the performance of the transmission as well as the other car's components.
The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU utilizes this signal to regulate fuel and boost, as well as timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms in these areas. This is a typical part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.