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How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is situated near the edges 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 located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located at the edges of the transmission, directly 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 flow of fuel, timig and boost. It also sends signals to the G5 tachometer inside the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC and also the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).

It's a bit tricky to test because there are various 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. When the sensor is fully operational, it should read about 1000 ohms. Look for signs of coolant, or oil in the connector bay if there are issues with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is running out of gas or injectors are not firing anymore. In the morning, i removed the spark plugs. Three were drenched with gazoline the 4th one was dry. I put tissue over each injector hole, and when I start the engine with no sparks, the three with gazoline jump right out. The 4th one stays closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get 0ohm. I think the issue is in another location.

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 coolant (G62) shows the wrong temperature value of -49c, even if I unplug it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.

I'm not certain what to do, but i believe that i've ruled out everything else. But i'm worried that i might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style sensor is the same as 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 wrecking yard or in a local parts store. Testing them is easy to do - just 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 left on the black connector's side). They should 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 the fuel injector, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these, the diagnostic scanner will show the codes that could trigger an engine shut down.

Some of the symptoms of a failed G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when in gear. If you are experiencing any of these problems, it is likely your sensor is deteriorating and should be replaced. They are cheap and easy-to-find especially when they're an Bosch unit like ours. Alternatively, the GM version of this part is also a good option.

5. Tachometer

A damaged engine sensor could cause a variety of issues within your vehicle. It is an important part of the transmission in your audi replacement keys keys replacement key for audi a3 cost, rust-client.ru, since it sends information to the ECU regarding how fast or slowly the car's engine is spinning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost as well as transmitting it to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [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 the same across the audi replacement key cost 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find good ones in wrecking yards.