How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission above the flywheel ring gear. It sends a signal to the ECU via an uncolored wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors.
If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in alignment 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. The code will not appear without the additional information provided by other sensors (G4 or G40).
It can be a bit difficult to test since there are several pins on the connector and they all have different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms if the sensor is in full operation. Check for evidence of coolant or oil in the connector bay if you are experiencing problems with this part.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at full speed, i noticed a huge decrease in power. It was like the engine was running out of gas. Or my injectors weren't firing. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. When I crank the engine without sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is here elsewhere.
I also tried to reset the PID but without success. The car will start when the G28 is disconnected and runs fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. I also noticed audi lost key that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when i rev the engine.
I don't know what to do. I feel like i've pretty much ruled everything else out. However, i'm afraid that i might have missed something. If anyone has any ideas please chime in! TIA!
3. Fuel Pump
The fuel pump of the g28 receives 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 why you can easily locate one at a junkyard 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 end facing up). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will show codes that could cause an engine shutdown.
The signs of a malfunctioning G28 sensor are an inaccurate gearbox rev counter, gears shifting quicker than normal, and/or a misfire when in gear. If you experience any of these issues, it is likely that your sensor is going bad and get more info needs replacing. The good news is they are quite affordable and easy to find, especially in the case of a Bosch sensor, 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 a cause for many issues in your car. It's an essential component of the transmission in your Audi because it relays information to the ECU regarding how fast click here or slow the car's engine is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.
The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU uses this signal to control fuel and boost, and also timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the here ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should detect an average resistance of 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU, so you might find them in wrecking yards.