10 Situations When You'll Need To Know About Audi G28
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal the ECU via the grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU utilizes this information to control fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.
If this sensor fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of the upper chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
It is a little tricky to test because there are different pins on the connector and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is functional, it should read about 1000 ohms. If you're having issues with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or audi key fob replacement were not firing. Today, i pulled out the spark plugs. Three were drenched in gazoline, the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine without sparks, the 3 with gazoline jump right out. The 4th one remains closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero Ohm. So i assume the problem is in another place.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62) even when unplugged, still shows temperatures of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, but i believe that i've ruled out everything else. I'm worried that i might have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or in a local parts store. It is easy to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They should 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 a decision about timing of the fuel injectors, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could lead to an engine shut down.
Some of the symptoms of a failing G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when in gear. It is likely that your sensor is failing and requires to be replaced if you notice any of these signs. They're cheap and easy to find especially when they're an Bosch sensor like ours. Alternatively, the GM version of this component is also a great option.
5. Tachometer
A failing engine sensor could cause a myriad of issues in your car. It's a crucial component of the transmission of your Audi because it relays information to the ECU regarding how fast or slowly the engine of the car is spinning. If the sensor fails, it will disrupt the performance of the transmission, as well as the other car's components.
The G5 engine speed sensor is located at the outside of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49, via a grey wire. The ECU then processes the signal to control the flow of fuel, timig and boost as well as sends it on to the G5 tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking 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. There should be an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du, so you might find good ones in wrecking yards.