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 edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear the G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails to function, 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 indicate an issue with the chain or a jumped chain link in the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).
Testing can be a bit difficult because there are two connector pins and they have different functions but the most effective way to test it is to measure the resistance between the sensor and the ECU. It should read approximately 1000 ohms if the sensor is at full operation. Look for evidence of coolant or oil in the connector bay if you have issues with this part.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum 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, 3 were drenched in gasoline and the 4th was dry. I put tissue over each injector hole and when I start the engine with no sparks, the three with gazoline jump right out. The 4th one remains closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero Ohm. I think the issue is somewhere else.
I also tried to reset the PID without success. The car will start when the G28 is unplugged and runs fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do. I think I've eliminated everything else. I'm afraid i may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from 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 which is why you can easily locate one at a wrecking yard or from a parts store. It is simple to test them: simply switch 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 should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires to know both the position and speed of the crankshaft in order to make a decision about fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these, the diagnostic scanner will show codes that could lead to the engine shutting down.
The signs of a malfunctioning G28 sensor include an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or a misfire when you're in gear. It is likely that the sensor is failing and requires to be replaced if you experience any of these symptoms. They're inexpensive and easy to locate particularly in the case of a Bosch model like ours. You can also choose the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind a slew of problems in your car. It's a crucial component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine of the car is turning. If the sensor fails, it could disrupt the performance of the transmission, as well as the other car's components.
audi a1 keys is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU is then able to process the signal to control the flow of fuel, timig and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 DU You may also find them in wrecking yards.