How to Replace Audi Key Fob an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated on the outside of the transmission, above the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49) and then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the outside of the transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 Tachometer located in the 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 also the location of the camshaft to trigger the spark and injectors.

If this sensor fails to function, the ECU will display a P00160 error message. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging because there are two connector pins and they have different functions but the best way to test it is to measure the resistance between the sensor and the ECU. If the sensor is operational, Replace audi key fob it should read about 1000 ohms. Check 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 a big cut in power as if the engine was running out of gas or injectors aren't firing any more. This morning i pull out the spark plugs. Three were drenched in gazoline, the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the ones with gazoline jump out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is in another place.

I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows an ice temperature of -49c. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 when I crank up the engine.

I'm not certain what to do, i think i've pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. If anyone has any suggestions, please chime in! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is identical to the G4 and they both work in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or at a parts store. It is simple to test them: simply put your DMM into resistance mode and determine 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 of our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft in order to make a decision about timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either one of these, Replace Audi Key Fob the diagnostic scanner will show codes that could cause the engine shutting down.

Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter, gears shifting quicker than normal and/or a misfire when you're in gear. It is likely that your sensor is failing and needs to be replaced if you encounter any of these symptoms. The good news is they are quite affordable and readily available, especially when you're looking at a Bosch unit which is what ours are. Alternatively, GM's version of this part is an excellent choice.

5. Tachometer

A failing engine sensor could cause a number of problems in your car. It's a crucial component of the transmission of your audi a1 key, as it transmits information to the ECU regarding how fast or slow the car's engine is spinning. This sensor could cause the transmission to fail 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 and sends a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to regulate the amount of fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by checking continuity from 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 [79trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see approximately 1000 ohms of resistance between those two pins. This is a standard part across the Audi 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.