How to Replace audi key replacement shows you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the outside of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know 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 out of sync, possibly indicating the chain stretching or a jump link on the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).
It's a bit tricky to test as there are several pins on the connector and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should read about 1000 ohms. If you are having problems with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is out of gas or the injectors are not firing anymore. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. When i crank the engine with no sparks i put tissue on the top of each of the injector holes and the 3 drenched with gazoline pop out, but the 4th one stays closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero ohm. Therefore, i think the issue is elsewhere.
I also tried to reset the PID without success. The car can start when the G28 is not plugged in and runs fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. I'm worried that i might have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars so you can easily find one at a junkyard or in a local parts store. It is simple to test them by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must know the speed and position of the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these, the diagnostic scanner will show codes that could lead to an engine shut down.
Some of the symptoms of a failing G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or a misfire when you are in gear. If you experience any of these issues it is most likely that your sensor is deteriorating and should be replaced. The good thing is that they are quite affordable and easily accessible particularly when you're looking at a Bosch model, which is what ours are. Alternatively, GM's version of this component is a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues in your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. When this sensor fails, it will affect the performance of the transmission, as well as the other car's components.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU is then able to process the signal to control fuel, timig, and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be the resistance to be around 1000 ohms in these areas. This part is common 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, so you might find good ones in wrecking yards.