Audi G28: The Good The Bad And The Ugly
How to Replace an audi q5 key G28 Engine Speed Sensor
Charles the Humble Technician shows you how to replace audi key the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate boost and fuel. It also sends signals to the G5 tachometer inside the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors in the right way.
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, possibly indicating the chain stretching or a jump link on the upper chain of timing. The code won't show without the additional information supplied by other sensors (G4 or G40).
It's a bit tricky to test because there are several connector pins, and they all have different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is functional, it should read about 1000 ohms. Look for evidence of coolant or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a significant decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. I put tissue over each injector hole, and when I start the engine without sparks, the 3 with gazoline jump right out. The 4th one stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I got 0ohm. So i assume the problem is elsewhere.
I also tried to reset PID but without success. The car can start when the G28 is not plugged in and runs fine when it is connected but it still has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c even when i unplug it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do. I feel like i've pretty much eliminated everything else. However, i'm afraid that I might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking 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 the 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 in order to make a decision about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner which could cause engine shut down.
A damaged G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, or an unfire when in gear. If you are experiencing any of these issues it is likely that your sensor is going bad and should be replaced. The good news is that they are very cheap and readily available, especially when you're looking at the Bosch unit which is what we have. Alternately, the GM version of this part is also a good option.
5. Tachometer
A damaged engine sensor could cause a myriad of issues in your vehicle. It is an important part of the transmission in your new audi key a5 key fob (relevant internet site) since it sends information to the ECU on how fast or slowly the engine is turning. 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 edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and replacement key for audi a3 processes this signal to control the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [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 a3 replacement key 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.