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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 at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster. 1. Engine Speed Sensor The grey wire is located at the edges of the transmission, just above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster. The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors according to the situation. If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain stretching or a jump link on the upper timing chain. However, the code won't appear on its own, without additional information from other sensors (G4 and G40). Testing is a bit tricky as there are two different pins for the connector and they have different functions however the best method to test it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. If you are having problems with this sensor, look for evidence of oil or coolant in the connector bay. 2. Injectors Yesterday, when accelerating from highway paytoll at full speed I noticed a massive decrease in power. It was as if the engine was running out of gas. Or my injectors weren't firing. Today, i pulled out the spark plugs, three were drenched in gazoline, the 4th one was dry. I put 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 tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming that the issue is somewhere else. I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero. I'm not sure what to do, i believe that i've eliminated 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 is activated by 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 from a parts store. Testing them is easy by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side 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 must be aware of the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. To do audi key replacement , it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can lead to engine shutdown. A damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, or a misfire in gear. It is possible that your sensor is failing and needs to be replaced if you encounter any of these symptoms. The good thing is that they are quite affordable and readily available, especially in the case of the Bosch unit which is what we have. Alternatively, the GM version of this part is also a great option. 5. Tachometer A failing engine sensor could cause a myriad of issues in your car. It is an important part of the transmission of your Audi since it sends information to the ECU about how fast or slow the car's engine is spinning. This sensor could cause the transmission to fail and other components in the car to be affected. The G5 engine speed sensor is located at the edge of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate the amount of fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer in instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.