How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission just above the flywheel ring 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
The grey wire is situated on the outside of the transmission, just above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to regulate fuel and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC and also where the camshaft lies to trigger the spark and injectors.
If this sensor fails, the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating chain stretch or a jumped link on the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging since there are two connector pins and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully functional, it should read about 1000 ohms. If you're experiencing issues with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge decrease in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. In the morning, i removed the spark plugs. Three were drenched in gazoline, the 4th one was dry. When I crank the engine with no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th one stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. I think the issue is somewhere else.
I also tried to reset the PID without success. The car will start if the G28 is not plugged in and it runs perfectly when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.
I'm not sure what to do. I think I've eliminated everything else. I'm concerned that i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is simple to test them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing up). how to get a new audi key should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either one of these, the diagnostic scanner will display codes that could cause an engine shut down.
Some of the signs of a failing G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or misfiring when you're in gear. If you are experiencing any of these issues it is likely that your sensor is deteriorating and requires replacement. They are cheap and easy-to-find particularly in the case of a Bosch model like ours. If you prefer, GM's version of this part would be an excellent choice.
5. Tachometer
A damaged engine sensor could cause a number of problems in your vehicle. 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. This sensor can cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU then uses and processes this signal to control fuel, timig, and boost and then transmitting 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 on pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU You may also find good ones in wrecking yards.