The Ultimate Cheat Sheet On Audi G28 How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor


Located on the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via an uncolored wire. The ECU uses this information to regulate fuel and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is 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 alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper chain of timing. However, the error code won't appear on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test because there are various pins on the connector, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms when the sensor is in full operation. Examine for signs of coolant, or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed I noticed a significant decrease in power. It was like the engine was running out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs. Three were drenched with gazoline the fourth one was dry. When I crank the engine without sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline pop out, but the 4th stay closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 I get 0ohm. I assume that the problem is elsewhere.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, i think i've pretty much completely ruled out all other possibilities. However, i'm afraid that I may have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal by the RPM sensor. more resources -style transmitter is the same as the G4 and both function in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or at a parts store. It is easy to test them: simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the speed and position of the crankshaft to make decisions about timing of the fuel injectors, etc. 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 sensors, the diagnostic scanner will show codes that could cause an engine shutdown.

A malfunctioning G28 sensor could result in an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, or a misfire while in gear. It is likely that your sensor is failing and needs to be replaced if you notice any of these signs. The good news is they are very cheap and readily available, especially in the case of the Bosch sensor, like ours. Alternatively, the GM version of this unit is also a good choice.

5. Tachometer

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

The G5 engine speed sensor is located at the outside of the transmission above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 through an uncolored wire. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also sends 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 [79trace [79]), and between pin T6a/1 and pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This is a common feature across the Audi 80-100-200-RS2 model, ranging from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU You may also find them in wrecking yards.