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How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. The sensor is situated at the top of the transmission above the flywheel ring gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also the location of the camshaft to trigger the spark and injectors.

If this sensor fails to function, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy 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 different pins on the connector and they all have different functions. The best way to do it is to measure the resistance between the ECU and audi replacement Key Cost uk the sensor. When the sensor is operational, it should be reading approximately 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had massive power loss like the engine is out of gas or injectors aren't firing at all. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth was dry. I put tissue over each injector hole, and when I turn the engine on without sparks, the three that have gazoline pop right out. The 4th one remains closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. Therefore, i think the issue is in another place.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is zero.

I'm not certain what to do, i believe that i've eliminated everything else. 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 in the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. It is simple to test them - just switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They should 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 to make decisions about fuel injector timing etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

A failing G28 sensor can cause an inaccurate speed counter for the gearbox, Audi Replacement Key Cost Uk a gearbox that shifts faster than normal, and/or a misfire while in the gear. If you are experiencing any of these problems, it is most likely that your sensor is failing and needs replacing. The good thing is that they are very affordable and easy to find, especially when you're looking at a Bosch unit like ours. Alternately, GM's version this component is an excellent choice.

5. Tachometer

A malfunctioning engine sensor can cause a myriad of issues within your vehicle. It's a vital component of the audi a3 key fob replacement's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is rotating. If this sensor fails, it will cause problems for the transmission as well as the other car's components.

The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU then uses and processes this signal to control fuel, timig, and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a standard component across the audi replacement key Cost uk 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.