How to Replace an audi key programmer G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using the grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors accordingly.

If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult since there are two pins for the connector and they serve different purposes but the best method to test it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is in full operation. Look for signs of coolant or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive reduction in power. It was as if the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. When i crank the engine with no sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th stay closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I found zero ohm. So i assume the problem is elsewhere.

I also tried to reset the PID but without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I'm not sure what to do, but i think i've pretty much ruled out everything else. I'm concerned that i may have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter is the same as the G4 and both are used in the 80 100 200, UrS and RS2 cars so you can easily find one at a wrecking yard or at a parts store. Testing them is easy - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black connector's end). They should be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must be aware of the speed and position of the crankshaft to make decisions about timing of the fuel injector, for example. It uses a Crank Position Sensor G4 and an Engine Speed Sensor Spare audi key G28 to achieve this. If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shut down.

A failing G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or a misfire in gear. It is possible that your sensor is failing and requires to be replaced if you notice any of these signs. The good news is that they are very cheap and easy to find particularly in the case of an Bosch sensor, which is what we have. Alternately, GM's version this part would be an excellent choice.

5. Tachometer

A failing engine speed sensor could be the cause of many issues with your vehicle. It is an important part of the transmission in your replacement audi key fob, as it transmits information to the ECU on how fast or slow the car's engine is turning. This sensor can cause the transmission to fail and other car components to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also sends it to the G5 Tachometer located in the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between 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 between these points. This part is common across the audi keyless go 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.