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The No. 1 Question Everyone Working In Audi G28 Should Know How To Answer
How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated near the transmission's edge over the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a 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 an indication to the G5 Tachometer in instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors in the right way.

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

It is a little tricky to test since there are several pins on the connector, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. If you are having problems with this component, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at full speed I noticed a significant decrease in power. It was like the engine was running out of gas. Or, my injectors weren't firing. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. I put a piece of tissue over each injector hole, and when I turn the engine on without sparks, the 3 with gazoline jump right out. The fourth one remains closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I think the issue is elsewhere.

replace audi key tried to reset PID but without success. The car can start when the G28 is disconnected and runs fine when it is connected however it has the intermittent misfire issue 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 0.

I'm not sure what to do, as i feel i have pretty much eliminated everything else. But i'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is identical to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. Testing them is easy to do - just put 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 left on the black connector's end). They must be infinite Ohms.

4. ECU


Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. To do this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go bad you will get codes on the diagnostic scanner which can cause the engine to shut down.

Some of the signs of a failed G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or misfiring when you are in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these symptoms. The good news is they are very affordable and easy to find, especially in the case of the Bosch unit which is what we have. Alternatively, GM's version of this part would be an excellent choice.

5. Tachometer

A failing engine speed sensor could be the reason behind a slew of issues in your vehicle. It's an essential component of your Audi's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor can cause the transmission to malfunction and other components of the car to be affected.

The G5 engine speed sensor is located on the outside of the transmission just above the flywheel ring gear and sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU utilizes this signal to regulate the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should detect a resistance of approximately 1000 ohms between these points. This is a standard part that is found across the Audi 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.

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