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 near the transmission's edge over the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49), then to the tachometer in 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 signals through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
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 the chain is stretched or a jump link on the upper timing chain. However, the 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 perform different functions but the most effective method of testing it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms when the sensor is operating at its maximum. If you're having issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. When I crank the engine, there are no sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. I'm assuming the issue is in another place.
I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant temperature sensor (G62) shows the here wrong temp value that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when 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 all other possibilities out. I'm afraid i may have missed something. Let me know if you have any ideas! TIA!
3. Fuel audi tt keys Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80, 100, 200, UrS and RS2 cars which is why you can here easily locate 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 at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
Our 20vt turbo website (3B AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft in order to make decisions about timing of the fuel injector, for example. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will show the codes that could trigger website an engine shutdown.
A malfunctioning G28 sensor can cause an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, or a misfire while in the gear. It is likely that your sensor is failing and requires to be replaced if you experience any of these signs. They're inexpensive and easy to locate particularly in the case of an Bosch model like ours. Alternatively, the GM version of this part is also a great option.
5. Tachometer
A malfunctioning engine sensor can cause a number of problems in your vehicle. It is an important part of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine of the car is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.
The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also check 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 detect the resistance to be around 1000 ohms between these points. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 Du You may also find them in wrecking yards.