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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 at the top of the transmission, above the flywheel ring gear. It sends a message to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. 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 must know when the crankshaft has reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails, the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump link on the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult because there are two connector pins, and they have different functions but the best way to test it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms if the sensor is in full operation. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or, my injectors were not firing. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the 4th was dry. I put tissue over each hole in the injector and when i turn the engine on without sparks, the ones with gazoline jump right out. The fourth one remains closed. I tested 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 elsewhere.
I also tried to reset the PID but without success. The car is able to start if the G28 is unplugged and is running fine when it is connected however it has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (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 0.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. I'm afraid i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. It is simple to test them to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to be aware of the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.
Some of the signs of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when you are in gear. It is probable that the sensor is failing and requires to be replaced if you experience any of these signs. audi car key replacement and easy to locate, especially if they're a Bosch model like ours. Alternately, the GM version of this component is also a great option.
5. Tachometer
A failing engine speed sensor could be a cause for a slew of issues with your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU about how fast or slowly the engine is turning. This sensor can cause the transmission to malfunction and other components in the car to be affected.
The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It 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 in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is a common part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.