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 sends a message to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. new audi key uses this information to control the boost, fuel, and timig. It also sends a signal to the G5 tachometer in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC and also the location of the camshaft to trigger the spark and injectors.
If this sensor fails the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky since there are two connector pins, and they perform different functions but the best way to test it is by measuring resistance between the sensor and the ECU. If the sensor is operational, it should be reading approximately 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 an abrupt drop in power 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 drenched in gasoline and the 4th was dry. When I crank the engine without sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline leap out, however the 4th one stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID but without success. The car can start when the G28 is not plugged in and is running fine when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not certain what to do, but i feel i have pretty much ruled out everything else. audi a1 keys '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 from the RPM sensor. The GM-style transmitter 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 wrecking yard or at a parts store. Test them out - put your DMM in resistance mode and measure the resistance 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). audi a1 key replacement must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must know the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, for example. 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 that can lead to engine shutdown.
A failing G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, and/or an unfire when in the gear. It is possible that your sensor is failing and needs to be replaced if you notice any of these symptoms. They're cheap and easy to find particularly if they're a Bosch sensor like ours. If you prefer, GM's version of this part would be an option.
5. Tachometer
A damaged engine sensor could cause a number of problems within your vehicle. It's an essential component of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components in the car to be affected.
The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to control the flow of fuel and boost as well as timig. It also sends it to the G5 Tachometer inside the 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 [79]), and between pin T6a/1 as well as pin T26a/12. You should detect an average resistance of 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find some good ones in wrecking yards.