How to Replace an audi a3 keys G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It sends a message to the ECU through an uncolored 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 an electrical signal to ECU pin T55/49 through the grey wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft has reached TDC and also the position cost of audi key replacement 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 not in alignment with the Intake Camshaft. It could also indicate a chain stretch or a jumped chain link in the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).

It can be a bit difficult to test since there are various connector pins, and each has its own functions. The best way to do it is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading around 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a significant drop 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 and found that 3 were soaked with gasoline 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, the 3 drenched with gazoline leap out, however the 4th stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero ohm. I assume that the problem is in another location.

I also tried to reset the PID but with no luck. The car can start if the G28 is not plugged in and runs fine when it is connected but it still has intermittent misfire issues at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is zero.

I'm not sure what to do, i feel i have pretty much eliminated everything else. I'm concerned that i may have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal by 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 which is why you can easily locate one at a junkyard or from 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 on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to be aware of the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either one of these, the diagnostic scanner will display codes that could lead to the engine shutting down.

A damaged G28 sensor could result in an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or a misfire while in the gear. If you have any of these issues, it is likely that your sensor is going bad and requires replacement. The good news is they are quite affordable and easy to find, especially in the case of a Bosch model, which is what ours are. Alternately, the GM version of this part is also a good choice.

5. Tachometer

A damaged engine sensor could cause a number of problems in your car. It's an essential component of the transmission in your audi spare key Smart Key Replacement, Gpsites.Win,, as it transmits information to the ECU on how fast or slow the car's engine is turning. This sensor could cause the transmission to fail and other components of the car to be affected.

The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to control fuel and boost, and also to timigrate. It also sends it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by examining the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is a common feature across the audi a3 spare key 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find some good ones in wrecking yards.