10 Mistaken Answers To Common Audi G28 Questions: Do You Know The Right Ones?
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 edges of the transmission, above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. audi a4 car key replacement uses this information to control the boost, fuel, and timig. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC, and the position of the camshaft, so that it can activate the spark and injectors.
If this sensor fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
Testing can be a bit difficult as there are two different connector pins, and they have different functions but the best way to test it is to measure the resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is operating at its maximum. If you are having problems with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were drenched in gazoline, the 4th one was dry. When I start the engine with no sparks i put tissue on top of each injector hole, the 3 drenched with gazoline jump out but the 4th stays shut. I checked the ground connection of ECU pins 14,30, and 48/55. I got 0ohm. I assume that the problem is in another location.
I also tried to reset PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do, i believe that i've ruled out everything else. I'm concerned that i may have missed something. Please let me know If you have any suggestions! 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 similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. It is simple to test them - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft to make a decision about timing of the fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes on the diagnostic scanner which can cause the engine to shut down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, and/or an unfire when in gear. It is likely that the sensor is failing and needs to be replaced if you encounter any of these signs. They are cheap and easy-to-find, especially when they're a Bosch model like ours. Alternately, GM's version this part would be an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for many issues in your vehicle. It is a crucial part of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is turning. When this sensor fails, it can disrupt the performance of the transmission as well as the rest of the car's components.
The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig, and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for failure by checking 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 [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms in these areas. This is a common component across the Audi 80 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones might be availble in wrecking yards.