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How to Replace an Audi G28 Engine Speed Sensor Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge over the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer located in the instrument cluster. 1. Engine Speed Sensor Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster. The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC and also the location of the camshaft to trigger the spark and injectors. If this sensor fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper chain of timing. However, the error code won't appear on its own without additional information from other sensors (G4 and G40). It's a bit tricky to test since there are several pins on the connector and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is in full operation. Check for evidence of coolant or oil in the connector bay if you are experiencing problems with this part. 2. Injectors Yesterday, when accelerating from highway paytoll at a high speed I noticed a massive decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I placed a tissue over each hole in the injector and when i turn the engine on without sparks, the ones that have gazoline pop right out. The fourth one remains closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. lost my audi car keys got 0ohm. So i assume the problem is elsewhere. I also tried to reset the PID without success. The car is able to start if the G28 is unplugged and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c, even if I unplug it. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine. I'm not sure what to do. I believe that I've eliminated everything else. But i am afraid I might have missed something. Let me know should you have any suggestions! TIA! 3. Fuel Pump The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and they both work in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is easy to test them: simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing up). They should be infinite Ohms. 4. ECU The ECU of our 20vt turbo (3B AAN ABY ADU) engines must be aware of the position and speed the crankshaft in order to make a decision about fuel injector timing, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down. A damaged G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, or a misfire in gear. If you are experiencing any of these issues it is likely your sensor is failing and requires replacement. They're cheap and easy to find particularly if they're a Bosch model like ours. Alternatively, GM's version of this component is a good option. 5. Tachometer A damaged engine sensor could cause a variety of issues within your vehicle. It's an essential component of your Audi's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor could cause the transmission to fail and other components of the car to be affected. The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU utilizes this signal to control fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer in instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This part is common across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du So, you may find good ones in wrecking yards.