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 near the transmission's edge just above the flywheel gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU uses this information to regulate boost and fuel. It also sends an alert to the G5 Tachometer located in the instrument cluster.
The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC, and where the camshaft lies in order to activate the spark and injectors.
If this sensor fails when it fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of sync 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 will not appear without the additional information supplied by other sensors (G4 or G40).
Testing is a bit challenging since there are two connector pins and they perform different functions however the best way to test it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should read about 1000 ohms. If you are having problems with this sensor, look for signs of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, three were soaked with gazoline and the fourth one was dry. When I start the engine with no sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline jump out but the 4th one stays shut. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got 0ohm. get more info I assume that the problem is elsewhere.
I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. 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, as i believe that i've completely ruled out all other possibilities. But i'm worried that I may have missed something. If anyone has get more info suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is easy to test them: simply put your DMM into click here resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines must know more info both 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 one of these, the diagnostic scanner will show codes that could cause click here an engine shut down.
A damaged G28 sensor can cause an inaccurate gearbox speed counter or a gearbox that shifts faster than normal, and/or a misfire in gear. It is possible that the sensor is failing and needs to be replaced if you experience any of these symptoms. The good thing is that they are very affordable and easily accessible, especially when you're looking at an Bosch sensor, which is what we have. Alternatively, GM's version of this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of a slew of problems in your car. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components in the car to be affected.
The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU utilizes this signal to regulate the amount of fuel and boost, and also timig. It also relays it to the G5 Tachometer in instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. There should be a resistance of approximately 1000 ohms between these two points. This is a common part across the Audi 80 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.