How to Replace an Audi G28 Engine Speed Sensor
In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is situated near the transmission's edge just above the flywheel gear. It sends a message 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, just above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to regulate boost and fuel. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.
If this sensor fails when it fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult since there are two connector pins and they serve different purposes however the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading approximately 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you are experiencing issues with this part.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or, my injectors were not firing. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth was dry. When i crank the engine without sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline jump out but the 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is elsewhere.
I also tried to reset the PID but with no luck. The car will start if the G28 is not plugged in and runs fine when it is plugged in however it has intermittent misfire issues at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed audi a1 key that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I think I've all lost audi key other possibilities out. I'm afraid i may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or at a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure the resistance between pins 1 (with get more info the bump on the connector's end up) and 2 (2nd from left on the black connector's side). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft to make a decision about fuel audi car key replacement injector timing etc. It makes use of 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 that can cause the engine to shut down.
The signs of a failed G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when in gear. If you experience any of these issues it is likely your sensor is going bad and needs replacing. They're inexpensive and easy to website locate, especially if they're an Bosch unit like ours. If you prefer, GM's version of this part would be a good option.
5. Tachometer
A failing engine speed sensor could be the reason behind many issues with your car. It's a vital component of your Audi's transmission, since it relays information to the ECU about how 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 located on the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to regulate fuel and boost, and also to timigrate. It also sends 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. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see approximately 1000 ohms of resistance between those two pins. This is a common part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.