How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. audi a1 key is located on the outside of the transmission, above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission 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 boost, fuel, and timig. It also sends an indicator to the G5 Tachometer within the instrument cluster.
The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors accordingly.
If this sensor fails the ECU will display the P00160 error, 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 error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky as there are two different pins for the connector and they perform different functions but the best method of testing it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should read around 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had massive power loss as if the engine was running out of gas or the injectors aren't firing at all. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the fourth 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 stays shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming that the issue is somewhere else.
I also tried to reset the PID but with no luck. The car can start when the G28 is unplugged and it runs perfectly when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. 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 feel i have pretty much completely ruled out all other possibilities. I'm concerned that i may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both function in the 80, 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is easy to test them - just 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 must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner that can cause the engine to shut down.
A failing G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or a misfire while in gear. It is probable that your sensor is failing and needs to be replaced if you experience any of these symptoms. They're cheap and easy to find particularly in the case of an Bosch sensor like ours. Alternatively, the GM version of this part is also a good choice.
5. Tachometer
A failing engine speed sensor could be the cause of numerous problems in your vehicle. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, as well as timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can check for sensor 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 observe approximately 1000 ohms of resistance between those two pins. This is a standard part across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.