How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49) and then to the tachometer located in 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 a signal to ECU pin T55/49 via a grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched or a jump link on the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult as there are two different connector pins, and they have different functions but the most effective method to test it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is operating at its maximum. If you're experiencing issues with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is out of gas or the injectors aren't firing at all. In the morning, i removed the spark plugs, 3 were drenched with gazoline the fourth one was dry. I put tissue over each hole in the injector and when i turn the engine on without sparks, the 3 with gazoline jump out. The fourth one remains closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. I assume that the problem is in another location.
I more info also tried to reset the PID without success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The audi a1 key replacement temperature sensor for coolant (G62) shows the wrong temp value -49c even when i unplug it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, i believe that i've completely ruled out all other possibilities. I'm afraid i may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is simple to test them - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to determine fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could lead to the engine shutting down.
A damaged G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or a misfire while in gear. It is possible that your sensor is failing and audi a1 key replacement needs to be replaced if you experience any of these symptoms. The good news is that they are quite affordable and easy to find, especially in the case of the Bosch sensor, which is what we have. Alternately, GM's version this part is an option.
5. Tachometer
A failing engine speed sensor could be the cause of many issues with your car. It's a crucial component of the transmission of your Audi, as it transmits information to the ECU on how fast or slow the engine of the car is spinning. If the sensor fails, it could disrupt the performance of the transmission, as well as the rest of the car's components.
The G5 engine speed sensor is located on the outside 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 utilizes this signal to control the amount of fuel and boost, and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and audi a1 keys pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is a standard part check here that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.