How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission over the flywheel gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer on 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 via a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors accordingly.
If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync, possibly indicating the chain is stretched or a jump 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's a bit tricky to test as there are various pins on the connector, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when it is operating at its maximum. If you're having issues with this part, check for signs of oil or coolant in the connector bay.
2. replace audi key The Keylab , while accelerating from the highway paytoll at maximum speed, i noticed a huge decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, three were soaked with gasoline and the 4th was dry. I placed a tissue over each injector hole and when I start the engine without sparks, the 3 with gazoline jump right out. The fourth 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 that the issue is elsewhere.
I also tried to reset the PID with no success. The car is able to start if the G28 is unplugged and it runs perfectly when it is plugged in however it has intermittent misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.
I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. Please let me know if you have any ideas! 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 similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. It is simple to test them - just switch 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
Our 20vt turbo (3B AAN, ABY, and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes on the diagnostic scanner that could cause engine shut down.
A malfunctioning G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts more quickly than normal, and/or an unfire when in gear. It is possible that the sensor is failing and requires to be replaced if you notice any of these signs. They're inexpensive and easy to locate especially when they're an Bosch unit like ours. Alternatively, the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine speed sensor could be the cause of a slew of issues with your car. It is a crucial part of the Audi's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is turning. If the sensor fails, it will disrupt the performance of the transmission and the other car's components.
The G5 engine speed sensor is situated on the edge of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU is then able to process this signal to regulate the flow of fuel, timig and boost as well as transmitting it to the G5 tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This is the same across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 DU You may also find some good ones in wrecking yards.