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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 situated near the transmission's edge over the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located 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 signals to ECU pin T55/49 using a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster. The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors accordingly. If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating chain stretch or a jumped link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40). Testing can be a bit difficult as there are two different connector pins, and they serve different purposes however the best method of testing it is to measure the resistance between the sensor and the ECU. If the sensor is operational, it should read about 1000 ohms. Examine for evidence of coolant or oil in the connector bay if there are problems with this part. 2. Injectors Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is running out of gas or the injectors aren't firing anymore. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the fourth one was dry. When I start the engine with no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stay closed. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. So i assume the problem is elsewhere. I also tried to reset PID but without success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However g28carkeys.co.uk persists 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 bar while the actual pressure is zero. I'm not sure what to do. I think I've all other possibilities out. However, i'm afraid that i might have missed something. Please let me know If you have any suggestions! TIA! 3. Fuel Pump The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sender 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 junkyard or in a local parts store. Test them out 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 The ECU of our 20vt turbo (3B AAN ABY) engines must know both the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will show codes that could lead to the engine shutting down. A damaged G28 sensor can cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire in the gear. If you are experiencing any of these issues it is most likely that your sensor is deteriorating and should be replaced. They're inexpensive and easy to locate, especially in the case of an Bosch sensor like ours. If you prefer, GM's version of this part is an option. 5. Tachometer A failing engine speed sensor could be the cause of a slew of issues in your vehicle. It's an essential component of the transmission in your Audi since it sends information to the ECU regarding how fast or slow the engine of the car is turning. This sensor could cause the transmission to fail and other car components to be affected. The G5 engine speed sensor is located on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through a grey wire. The ECU is then able to process this signal to control the flow of fuel, timig and boost and then sends it on to the G5 tachometer inside the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. You should see an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du You may also find some good ones in wrecking yards.