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. The sensor is located near the edges of the transmission just above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 tachometer inside the instrument cluster.
The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft reached TDC and also the location of the camshaft in order to activate the spark and injectors.
If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and possibly indicating chain stretch or a jumped link on the upper timing chain. However, the error code won't be displayed on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are different connector pins, and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when it is at full operation. If you are having problems with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll, i experienced massive power loss like the engine is running out of gas or injectors are not firing at all. This morning i pull out the spark plugs, three were drenched with gazoline the 4th one was dry. I placed a tissue over each hole in the injector and when I start the engine without sparks, the 3 with gazoline jump right out. The 4th one remains closed. I checked the ground connection 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 but with no luck. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
audi a4 key replacement don't know what to do. I think I've ruled everything else out. But i'm worried that I might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or 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 on the connector's edge facing upwards). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft to make decisions regarding fuel injector timing etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.
A damaged G28 sensor could cause an inaccurate speed counter for your gearbox, a gearbox that shifts more quickly than normal, or a misfire in gear. It is probable 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 an Bosch model like ours. Alternatively, the GM version of this unit is also a good option.
5. Tachometer
A failing engine speed sensor could be the cause of numerous issues with your car. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how fast or slow the car's crankshaft is turning. This sensor can cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU is then able to process this signal to control the flow of fuel, timig and boost and then sends it on 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]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a typical component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.