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. The sensor is located on the outside of the transmission just above the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
Located on 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 the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. audi a5 replacement key must know when the crankshaft reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit tricky because there are two pins for the connector and they perform different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read around 1000 ohms when it is at full operation. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced a big cut in power as if the engine was running out of gas or the injectors are not firing any more. I pulled out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. I put a piece of tissue over each injector hole and when I turn the engine on without sparks, the ones with gazoline jump out. The fourth one remains closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. So i assume audi a5 replacement key is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. Also i noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not certain what to do, i feel i have pretty much ruled out everything else. I'm afraid i may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both function in the 80 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or in a local parts store. Test them out - put your DMM in resistance mode and take measurements 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 must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed the crankshaft to determine fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will display codes that could cause an engine shut down.
A failing G28 sensor can cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or an unfire when in gear. It is probable that the sensor is failing and needs to be replaced if you notice any of these symptoms. They're inexpensive and easy to locate, especially when they're an Bosch model like ours. Alternately, the GM version of this component is also a good option.
5. Tachometer
A failing engine sensor could cause a myriad of issues within your vehicle. It is an important part of the transmission in your Audi because it relays information to the ECU about how fast or slowly the car's engine is turning. If this sensor fails, it could disrupt the performance of the transmission and the other car's components.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits signals via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, 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 observe around 1000 ohms of resistance between those two pins. This is the same across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find good ones in wrecking yards.