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 on the outside of the transmission over the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indicator to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.
If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper chain of timing. The code won't show without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test as there are several pins on the connector, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power as if the engine was running out of gas or the injectors are not firing anymore. Today, i pulled out the spark plugs, three were soaked with gazoline and the fourth was dry. I placed a tissue over each injector hole, and when I start the engine with no sparks, the ones that have gazoline pop right out. The 4th one remains shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I'm assuming that the issue is in another location.
I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.
I'm not sure what to do, i believe that i've completely ruled out all other possibilities. I'm concerned that i may 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 by the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily locate an extra in a wrecking shop or a parts store. It is simple to test them by putting 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
The ECU in our 20vt turbo (3B AAN ABY) engines requires to know the speed and position of the crankshaft to determine fuel injector timing, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.
A failing G28 sensor could result in an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, or a misfire in the gear. It is likely that your sensor is failing and needs to be replaced if you experience any of these symptoms. They're cheap and easy to find especially when they're an Bosch sensor like ours. Alternatively, GM's version of this part is more info an excellent choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your vehicle. It is an important part of the transmission of your Audi because it relays information to the ECU on how fast or slow the engine of the car is spinning. This sensor can cause the transmission to fail and other components of the car to be affected.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits an electrical signal through a gray wire to get more info the ECU pin T55/49. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also relays it 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 website also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 audi a1 car key (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be the resistance to be around 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du So, you may find here some good ones in wrecking yards.