How to Replace an audi key programming G28 Engine Speed Sensor

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

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using an uncolored wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.

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

It can be a bit difficult to test since there are several pins on the connector, and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is at full operation. If you are having problems with this part, check for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a significant drop in power. It was like the engine had run out of gas. Or my injectors were not firing. I took out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. I placed a tissue over each hole in the injector and when i start the engine with no sparks, the 3 with gazoline jump out. The 4th one stays shut. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I got zero Ohm. So i assume the problem is somewhere else.

I also tried to reset the PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is zero.

I'm not sure what to do, as i think i've pretty much eliminated everything else. However, i'm afraid that I may have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent from the RPM sensor. The GM-style sensor is identical to the G4 and they both work in the 80, Audi Car Key Cover 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or in a local parts store. It is easy to test them - just switch your DMM into resistance mode and measure 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 ADU) engines requires to be aware of the position and speed the crankshaft in order to make a decision about timing of fuel injectors, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes badly, you will see codes on the diagnostic scanner which could cause engine shut down.

A damaged G28 sensor could cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, and/or an unfire when in the gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these signs. They are cheap and easy-to-find particularly if they're a Bosch model like ours. Alternately, GM's version this component is a good option.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous problems in your vehicle. It is a crucial part of your audi car Key cover's transmission, as it sends information to the ECU about how the car's crankshaft is rotating. When this sensor fails, it will affect the performance of the transmission, as well as the rest of the car's components.

The G5 engine speed sensor Audi car Key cover is located at the edge of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to control fuel and boost, as well as timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. You can also 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 resistance between those two pins. This is a typical part that is found across the Audi 80, 100, 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.