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 situated near the edges of the transmission above the flywheel ring 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 situated at the edges of the transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and the position of the camshaft, to trigger the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult because there are two connector pins, and they perform different functions but the best method of testing it is by measuring resistance between the sensor and the ECU. When the sensor is fully operational, it should read about 1000 ohms. If you're having issues with this sensor, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a significant reduction in power. It was as if the engine was running out of gas. Or my injectors weren't firing. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the 4th was dry. When I start the engine, there are no sparks, i place a tissue on the top of each of the injector holes, the 3 drenched with gazoline pop out, but the 4th one stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. Therefore, i think the issue is in another place.
I also tried to reset PID but without success. The car will start when the G28 is unplugged and is running fine 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. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I believe that I've eliminated everything else. But i'm worried that I might have missed something. If anyone has suggestions, please let me know! TIA!
3. audi a1 car key in the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and they both work in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. Testing them is easy - put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's end). genuine audi key replacement should be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft to make a decision about fuel injector timing etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.
Some of the symptoms of a failing G28 sensor are an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when you are in gear. If you experience any of these issues it is most likely that your sensor is going bad and should be replaced. They're inexpensive and easy to locate particularly if they're a Bosch unit like ours. Alternatively, GM's version of this component is an option.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your car. It's an essential component of the transmission in your Audi, as it transmits information to the ECU on how fast or slow the car's engine is spinning. If this sensor fails, it will disrupt the performance of the transmission as well as the rest of the car's components.
The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends a signal via an uncolored wire to the ECU pin T55/49. The ECU is then able to process the signal to control fuel, timig, and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 and pin T26a/12. You should see approximately 1000 ohms resistance between these two points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du So, you may find them in wrecking yards.