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 outside of the transmission over the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) and then to the tachometer within the instrument cluster.
1. Engine Speed Sensor
The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. 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 start spark and injectors according to the situation.
If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync, possibly indicating chain stretch or a jumped link on the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test because there are various pins on the connector and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. If the sensor is functional, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if you are experiencing issues with this component.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a significant reduction in power. It was like the engine was running out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs, 3 were drenched with gazoline the fourth was dry. When i crank the engine without sparks i put tissue on the top of each hole in the injector and the 3 drenched with gazoline jump out but the 4th stay closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I'm assuming the issue is somewhere else.
I also tried to reset the PID without success. The car can start if the G28 is disconnected and runs fine when it is connected but it still has intermittent misfire issues at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.
I'm not sure what to do. I feel like i've pretty much all other possibilities out. However, i'm afraid that i might have missed something. If anyone has any suggestions, please share them! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. It is simple to test them: simply put 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
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.
Some of the symptoms of a failed G28 sensor include an inaccurate rev counter for the gearbox and gears that shift faster than normal, and/or a misfire when you're in gear. It is possible that your sensor is failing and requires to be replaced if you experience any of these symptoms. They're cheap and easy to find particularly in the case of an Bosch sensor like ours. Alternately, GM's version this part is a good option.
5. Tachometer
A damaged engine sensor could cause a number of problems within your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU about how fast or slowly the engine is spinning. audi key replacement could cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU then uses and processes this signal to control fuel, timig, and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect a resistance of approximately 1000 ohms between these two points. This is a standard part that is found across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.