How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission above the flywheel ring gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU uses this information to regulate boost and fuel. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult since there are two pins for the connector and they perform different functions however the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read about 1000 ohms. If you're experiencing issues with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive reduction in power. It was like the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When i crank the engine without sparks, I put a piece of tissue on the top of each of the injector holes and the 3 drenched with gazoline jump out but the 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero Ohm. I'm assuming that the issue is in another location.
I also tried to reset PID but without success. The car is able to start if the G28 is not plugged in and is running fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.
I'm not sure what to do, but i think i've pretty much ruled out everything else. But i am afraid I might have missed something. Let me know If 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 identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. audi a1 car key can easily find a spare in a wrecking shop or parts store. Testing them is easy to do - just 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 the left on the black end of the connector). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will display codes that could lead to the engine shutting down.
The signs of a failed G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when you are in gear. It is possible that your sensor is failing and requires to be replaced if you notice any of these symptoms. They are cheap and easy-to-find especially when they're a Bosch model like ours. Alternatively, the GM version of this unit is also a great option.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of a slew of issues with your vehicle. It's an essential component of the transmission in your Audi since it sends information to the ECU on how fast or slowly the car's engine is turning. This sensor can cause the transmission to fail and other components in 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 the signal to control 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. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. It should show approximately 1000 ohms resistance between these two points. This part is common across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.