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 on the outside of the transmission just above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. 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 has to know when the crankshaft reached TDC, and the location of the camshaft to trigger the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jump in the chain link of the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test because there are various pins on the connector and each has its own 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 if the sensor is in full operation. Look for evidence of coolant or oil in the connector bay if you have problems with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive drop in power. audi key replacement cost The Keylab was as if the engine was running out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs. Three were soaked with gazoline and the 4th one was dry. When I start the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I think the issue is in another location.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it is running fine with the G28 plugged in. However, the intermittent misfire problem 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 shows 2 bar while the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do, as i believe that i've completely ruled out all other possibilities. I'm worried that i might have missed something. If anyone has any ideas please let me know! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80 100 200, UrS and RS2 cars so you can easily find one at a junkyard or in a local parts store. It is easy to test them - just put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will show codes that could lead to the engine shutting down.
Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal and/or misfiring when you are in gear. It is likely that the sensor is failing and needs to be replaced if you encounter any of these symptoms. The good news is they are quite affordable and readily available particularly if you're looking at a Bosch model, like ours. You can also choose the GM version of this component is also a good option.
5. Tachometer
A failing engine speed sensor could be a cause for many 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 turning. This sensor could cause the transmission to fail and other components of the car to be affected.
The G5 engine speed sensor is located at the outside of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through an uncolored wire. 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 for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can verify continuity between pin 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 the resistance to be around 1000 ohms between these two points. This part is common across the Audi 80-100-200-RS2 series, starting 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.