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. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer located on the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors accordingly.
If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test as there are several pins on the connector, and each has its own functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. If the sensor is functional, it should read about 1000 ohms. Check for signs of coolant or oil in the connector bay if there are problems with this part.
2. Injectors
Yesterday, while accelerating at full speed from the highway paytoll, i experienced massive power loss like the engine is running out of gas or injectors are not firing at all. I pulled out the spark plugs this morning, three were soaked with gasoline and the 4th was dry. I put a piece of tissue over each injector hole and when i start the engine without sparks, the three that have gazoline pop right out. The 4th one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I'm assuming that the issue is elsewhere.
I also tried to reset the PID but without success. The car can start if the G28 is disconnected and is running fine when it is plugged in but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when unplugged, still shows a temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, as i believe that i've eliminated everything else. However, i'm afraid that i might have missed something. If anyone has any ideas please share them! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or parts store. It is simple to test them to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from left on the black end of the connector). They should be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown.
A failing G28 sensor could result in an inaccurate gearbox speed counter or a gearbox that shifts more quickly than normal, or an unfire more info when in the gear. It is likely that your sensor is failing and requires to be replaced if you encounter any of these signs. The good news is that they are very affordable and easy to find, especially when you're looking at an Bosch sensor, like ours. Alternatively, GM's version of this part would be a good option.
5. Tachometer
A failing engine speed sensor could be the cause of a slew of issues with your car. It's a vital component of your Audi's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor could cause the transmission to fail and other car components to be affected.
The G5 engine speed sensor is here located at website the edge of the transmission above the flywheel ring gear and sends a signal to the ECU at pin T55/49 through a grey wire. The ECU utilizes this signal to regulate the amount of fuel and boost, and also timig. It also sends it to the G5 Tachometer in instrument cluster. You can read more test the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS audi car key An and 1995 RS2 Du You may also find good ones in wrecking yards.