How to Replace an key audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission over the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49), then to the tachometer in 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 signals to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used as a reference point to connect 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 in the right way.
If this sensor fails to function, the ECU will display a P00160 error code. This means that the Crank Shaft is not in alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jumped chain link in the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
It is a little tricky to test as there are various pins on the connector, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is operating at its maximum. If you're experiencing issues with this component, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or, my injectors weren't firing. Today, i pulled out the spark plugs. Three were soaked with gazoline and the 4th one was dry. I put a piece of tissue over each hole in the injector and when i start the engine with no sparks, the three with gazoline jump right out. The fourth one remains shut. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 I get zero ohm. I assume that the problem is in another location.
I also tried to reset the PID without success. The car will start when the G28 is disconnected, audi etron key; qooh.me, but it runs fine with the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c even when i unplug it. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.
I'm not sure what to do. I think I've eliminated everything else. I'm afraid i may have missed something. Please let me know should you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sensor 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 wrecking yard or at a parts store. It is easy to test them - simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines requires to be aware of the speed and position of the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these goes bad you will get codes on the diagnostic scanner that can cause the engine to shut down.
A failing G28 sensor could cause an inaccurate gearbox speed counter, a gearbox that shifts faster than normal, or a misfire while in the gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these signs. They are cheap and easy-to-find particularly in the case of an Bosch unit like ours. Alternatively, GM's version of this part would be an excellent choice.
5. Tachometer
A failing engine sensor could cause a myriad of issues in your vehicle. It is a crucial part of your audi Replacement Key Fob's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor can cause the transmission to malfunction and other car components to be affected.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those two pins. This is a common feature across the audi replacement key cost uk 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find some good ones in wrecking yards.