How to Replace an audi replacement keys G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located at the edge of transmission over the flywheel gear. It transmits a signal the ECU via an uncolored wire (T55/49) and then to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, just above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also where the camshaft lies so that it can activate the spark and injectors.

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

It's a bit tricky to test since there are different pins on the connector and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is at full operation. If you're experiencing issues with this sensor, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, i experienced a big cut in power like the engine is out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. When I start the engine with no sparks i put tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th one stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. Therefore, i think the issue is somewhere else.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, audi replacement key service and it runs fine with the G28 plugged in. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.

I'm not sure what to do. I feel like i've pretty much all other possibilities out. But i'm worried that I might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal by the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or in a local parts store. Test them out - 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 end of the connector). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines requires to know both the speed and position of the crankshaft to determine fuel injector timing, etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.

Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. It is probable that the sensor is failing and needs to be replaced if you notice any of these symptoms. They're cheap and easy to find, especially if they're a Bosch unit like ours. If you prefer, GM's version of this part would be an excellent choice.

5. Tachometer

A malfunctioning engine sensor can cause a variety of issues within your vehicle. It's a crucial component of the transmission of your audi key blade since it sends information to the ECU about how fast or slowly the car's engine is turning. This sensor can cause the transmission to fail and other car components to be affected.

The G5 engine speed sensor is located on the outside of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU uses this signal to control fuel and boost, as well as timig. It also relays it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by examining the 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 pin T6a/1 and the instrument cluster pin T26a/12. There should be the resistance to be around 1000 ohms in these areas. This is a common feature across the audi replacement key service 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU, so you might find some good ones in wrecking yards.