Audi G28: The Good, The Bad, And The Ugly How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge, above the flywheel gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, just above the flywheel ring. The sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control the amount of fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

audi q7 car key replacement is used as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC, and the location of the camshaft to trigger the spark and injectors.

If audi q5 locked keys in car fails when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in 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 won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging since there are two connector pins, and they perform different functions but the most effective method of testing it is to measure the resistance between the sensor and the ECU. When the sensor is operational, it should read around 1000 ohms. If you are having problems with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power as if the engine was running out of gas or the injectors aren't firing any more. I pulled out the spark plugs this morning, three were soaked in gasoline, and the 4th was dry. When I start the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 drenched with gazoline leap out, however the 4th one stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get 0ohm. I'm assuming the issue is somewhere else.

I also tried to reset the PID but with no luck. The car can start when the G28 is not plugged in and it runs perfectly when it is plugged in, but still has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.


I'm not sure what to do. I believe that I've ruled everything else out. I'm afraid i may have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style transmitter 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 - just put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They must be infinite ohms.

4. ECU

audi keys replacement (3B AAN, ABY, and ADU) engines are equipped with an ECU that has to be aware of the speed and position of the crankshaft in order to make decisions about timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

Some of the signs of a failed G28 sensor include an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when you're in gear. It is possible that your sensor is failing and requires to be replaced if you encounter any of these signs. They're cheap and easy to find, especially in the case of a Bosch model like ours. You can also choose the GM version of this component is also a great option.

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 the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor could cause the transmission to fail and other components in the car to be affected.

The G5 engine speed sensor is located at the outside of the transmission 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, as well as timig. It also relays it to the G5 Tachometer in instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, 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. You should detect an average resistance of 1000 ohms between these two points. This part is common across the Audi 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 DU You may also find some good ones in wrecking yards.