How to Replace an Audi 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, above the flywheel gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to control fuel 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 must be aware when the crankshaft is TDC and where the camshaft is located so that it can start spark and injectors accordingly.

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

Testing is a bit challenging because there are two connector pins, and they perform different functions but the best method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. Examine for signs of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. When I start the engine without sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline pop out, but the 4th one stays shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. So i assume the problem is somewhere else.

I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge audi a1 key replacement in the cockpit shows 2 bars while the actual pressure is zero.

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

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent by the RPM sensor. The GM-style transmitter is similar to the G4 sender and works click here on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or parts store. It is simple to test them by putting your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's side up) and 2 (2nd from the spare audi key left on the black connector's end). They must be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go bad you will get codes advanced key audi on the diagnostic scanner that can lead to engine shutdown.

Some of the symptoms of a failing G28 sensor are an inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when you're in gear. It is possible that the sensor is failing and needs to be replaced if you encounter any of these signs. They're inexpensive and easy to locate especially in the case of a Bosch unit like ours. Alternatively, GM's version of this part would be a good option.

5. Tachometer

A damaged engine sensor could cause a myriad of issues within your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slow the car's engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to control the flow of fuel and boost and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This is a common feature across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN click here and 1995 RS2 Du So, you may find them in wrecking yards.