How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows you 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 signal to the ECU via a grey wire (T55/49), then to the tachometer located in 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 a signal to ECU pin T55/49 via a grey wire. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC, and where the camshaft lies so that it can activate the spark and injectors.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper timing chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing can be a bit difficult as there are two different connector pins and they have different functions but the most effective way to test it is to measure resistance between the sensor and the ECU. When the sensor is fully functional, it should read approximately 1000 ohms. Look for signs of coolant, or oil in the connector bay if you have problems with this part.
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 are not firing anymore. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. I placed a tissue over each hole in the injector and when i start the engine without sparks, the three that have gazoline pop right out. The 4th one remains shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I'm assuming the issue is elsewhere.
I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.
I'm not sure what to do. I think I've ruled everything else out. But i'm worried that I might have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from a parts store. Testing them is easy by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's side up) and 2 (2nd from the left on the black connector's side). They must be infinite Ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to know the position and speed of the crankshaft in order to make a decision about fuel injector timing etc. It makes use of 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 lost audi key that could lead to the engine shutting down.
A malfunctioning G28 sensor could cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, and/or a misfire while in gear. It is possible that the sensor is failing and needs to be replaced if you notice any of these signs. They're inexpensive and easy to locate particularly in the case of a Bosch model like ours. If you prefer, GM's version of this part is an excellent choice.
5. Tachometer
A failing engine speed sensor could read more be the reason behind numerous problems in your car. It's an essential component of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is spinning. This sensor can cause the transmission to malfunction 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. It sends a signal audi a1 key replacement to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to regulate the flow of fuel and boost as well as timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it more info and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well more info as between T6a/1, and the instrument cluster pin T26a/12. You should see approximately 1000 ohms of resistance between those points. This is a common feature across the Audi 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 DU, so you might find good ones in wrecking yards.