Audi G28: The Good, The Bad, And The Ugly
How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the edge of transmission over the flywheel gear. It transmits a signal to the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated on the outside of the transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors according to the situation.
If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
It's a bit tricky to test because there are different pins on the connector and they all have different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when it is in full operation. Look for evidence of coolant or oil in the connector bay if there are issues with this component.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was unclean. When I start the engine, there are no sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. audi q7 car key replacement think the issue is somewhere else.
I also tried to reset the PID with no success. The car will start if the G28 is unplugged and is running fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.
I'm not sure what to do. I believe that I've ruled everything else out. I'm concerned that i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or a parts store. It is easy to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY ADU) engines requires to know both the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will show the codes that could trigger an engine shut down.
A failing G28 sensor could cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, or a misfire while in the gear. audi q7 keys locked in car is likely that the sensor is failing and requires to be replaced if you notice any of these symptoms. They're cheap and easy to find especially in the case of an Bosch model like ours. You can also choose the GM version of this unit is also a good option.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind many problems in your vehicle. It's a crucial component of the transmission in your Audi since it sends information to the ECU about how fast or slow the engine of the car is turning. If the sensor fails, it will disrupt the performance of the transmission, as well as the other car's components.
The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU then uses and processes this signal to control fuel, timig, and boost, and also transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This part is common 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 some good ones in wrecking yards.