How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission over the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using a grey wire. The ECU utilizes this information to regulate boost and fuel. It also sends a signal to the G5 Tachometer located in the instrument cluster.
The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.
If this sensor fails, the ECU will throw a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and possibly indicating the chain is stretched or a jump link on the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky because there are two connector pins, and they serve different purposes but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is operating at its maximum. Look for signs of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge drop in power. It was like the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning, 3 were soaked with gasoline and the 4th was dry. When I start the engine, there are no sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline jump out but the 4th stays closed. I tested the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero Ohm. Therefore, i think the issue is in another place.
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 click here sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.
I'm not certain what to do, i feel i have pretty much eliminated everything else. But i am click here afraid I might have missed something. Let me know should you have any suggestions! 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 both function in the 80 100 200, UrS and RS2 cars which is click here why you can easily locate one at a salvage yard or at a parts store. It is easy 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 the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you are experiencing issues with either of these, the diagnostic scanner will show codes that could lead to an engine shut down.
A failing G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, or an unfire when in the gear. If you have any of these problems, it is likely your sensor is failing and should be replaced. The good news is they are quite affordable and readily available, especially when you're looking at the Bosch unit which is what we have. Alternatively, GM's version of this component is an option.
5. Tachometer
A failing engine speed sensor could be the cause of numerous issues with your car. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slow the engine is turning. When this sensor fails, it can disrupt the performance of the transmission as well as the rest of the car's components.
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, via an uncolored wire. The ECU uses this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect the resistance to here be around 1000 ohms in these areas. This is a common part across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 website ADU, so the best parts could be found in wrecking yards.