How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge over the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, directly above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 tachometer in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and the position of the camshaft, in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins and they have different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. When the sensor is functional, it should read approximately 1000 ohms. If you're experiencing issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive reduction in power. It was as if the engine was running out of gas. Or my injectors were not firing. I took out the spark plugs this morning and found that 3 were soaked with gasoline and the 4th was dry. When i crank the engine with no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline leap out, however the 4th stays shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get 0ohm. I'm assuming the issue is elsewhere.
I also tried to reset the PID but with no luck. The car can start if the G28 is unplugged and is running fine when it is connected however it has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if audi replacement keys I unplug it. here Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I'm not certain what to do, i believe that i've eliminated everything else. I'm afraid i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the website 80, 100, 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. It is simple to test them: simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines needs here to know both the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.
A damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or a misfire while in the gear. If you have any of these problems, it is most likely that your sensor is going bad and should be replaced. The good news is they are quite affordable and readily available particularly when you're looking at an Bosch model, which is what ours are. If you prefer, GM's version of this component is an excellent choice.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It's a vital component of your Audi's transmission, because it communicates to the ECU about how fast or slow the car's crankshaft is spinning. When this sensor fails, it can cause problems for the transmission, as well as the other car's components.
The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin replacement car key audi T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This is a typical component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.