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How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you 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 to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, just above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to control fuel and boost. It also sends signals to the G5 tachometer inside the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft reached TDC and also the location of the camshaft in order to activate the spark and injectors.

If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit challenging since there are two pins for the connector and they have different functions but the best method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is operating at its maximum. If you're having issues with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed I noticed a significant reduction in power. It was like the engine was running out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs, three were soaked with gazoline and the fourth was dry. When I crank the engine with no sparks i put tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th one stays closed. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I think the issue is somewhere else.

I also tried to reset the PID without success. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value -49c, even if I unplug it. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do, but i believe that i've completely ruled out all other possibilities. However, i'm afraid that i might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. It is easy to test them: simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

A damaged G28 sensor could cause an inaccurate speed counter for your gearbox and a gearbox which shifts faster than normal, and/or an unfire when in gear. If you are experiencing any of these issues, it is most likely that your sensor is going bad and requires replacement audi key. They're cheap and easy to find, especially when they're an Bosch unit like ours. Alternately, GM's version this component is an excellent choice.

5. Tachometer

A malfunctioning engine sensor can cause a number of problems in your car. It's a crucial component of the transmission of your audi a3 key fob replacement, as it transmits information to the ECU regarding how fast or slow the engine of the car is turning. 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 just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to control the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms of resistance between those two pins. This is a standard part that is found across the audi tt key fob 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.