How to Replace an Audi G28 Engine Speed Sensor Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is located on the edge 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 in the instrument cluster. 1. Engine Speed Sensor It is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster. The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors according to the situation. If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40). It's a bit tricky to test as there are different pins on the connector, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is at full operation. If you are having problems with this component, look for evidence of coolant or oil in the connector bay. 2. Injectors Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or, https://doganharbo61.livejournal.com/profile were not firing. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the fourth was dry. When I start the engine without sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline pop out, but the 4th stay closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is in another place. I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine. I don't know what to do. I feel like i've pretty much ruled everything else out. However, i'm afraid that I might have missed something. If anyone has suggestions, please chime in! TIA! 3. Fuel Pump The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style transmitter is the same as 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 at a parts store. It is easy to test them: simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite Ohms. 4. ECU The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the speed and position of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown. A damaged G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or a misfire while in gear. If you are experiencing any of these issues it is most likely that your sensor is failing and should be replaced. The good thing is that they are very cheap and easy to find, especially if you're looking at the Bosch model, like ours. Alternatively, GM's version of this component is an excellent choice. 5. Tachometer A faulty engine speed sensor could be a cause for a slew of problems in your vehicle. It's a vital component of the Audi's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components of 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 transmits a signal to the ECU at pin T55/49 through a grey wire. The ECU then uses and processes the signal to control fuel, timig, and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can examine the continuity between pins 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 detect the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU You may also find them in wrecking yards.