How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge over the flywheel gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, just above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. 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 reached TDC, and where the camshaft lies to trigger the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper chain. 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 various connector pins, and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. If you are having problems with this part, check for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors aren't firing anymore. I pulled out the spark plugs this morning, 3 were soaked with gasoline and the fourth was dry. I put a piece of tissue over each hole in the injector and when i turn the engine on without sparks, the three with gazoline jump out. The 4th one remains shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero ohm. I assume that the problem is somewhere else.
I also tried to reset the PID but with no luck. The car will get more info start when the G28 is not plugged in and runs fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do. I replace audi key feel like i've pretty much eliminated everything else. But i'm worried 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 from the RPM sensor. The GM-style sensor is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or from a parts store. It is simple to test them - simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo more info (3B AAN ABY ADU) engines must be aware of the speed and position of the crankshaft to determine timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.
Some of the symptoms of a failing G28 sensor include an check here inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when you are in gear. It is likely that your sensor is failing and needs to be replaced if you experience any of these symptoms. The good news is that they are quite affordable and easy to find, especially in the case of a Bosch sensor, which is what we have. Alternately, GM's version this part would be a good option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of problems in your car. It is an important part of the transmission in your Audi since it sends information to the ECU about how fast or slow the engine is turning. If this sensor fails, it could affect the performance of the transmission and the other car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig, and boost and then 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. Additionally, 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 as well as pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find read more them in wrecking yards.