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The Most Convincing Evidence That You Need Audi G28
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. This sensor is located near the edges of the transmission just above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the outside of the transmission, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to control the amount of fuel and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft reached TDC and also where the camshaft lies to trigger the spark and injectors.

If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging because there are two connector pins, and they perform different functions but the most effective method of testing it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms when the sensor is operating at its maximum. If you're experiencing issues with this component, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, i experienced a big cut in power like the engine is out of gas or injectors aren't firing anymore. In the morning, i removed the spark plugs, 3 were drenched with gazoline the fourth was dry. When i crank the engine without sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stay closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I think the issue is elsewhere.

I also tried to reset PID without success. replacement car key audi will start when the G28 is disconnected and is running fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I'm not sure what to do. I think I've ruled everything else out. But i am afraid i might have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing up). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to know the position and speed of the crankshaft in order to make decisions regarding fuel injector timing etc. In order to do this it utilizes 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 damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or an unfire when in gear. It is possible that your sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is that they are quite affordable and easy to find, especially in the case of an Bosch sensor, like ours. Alternatively, GM's version of this component is an option.

5. Tachometer


A damaged engine sensor could cause a variety of issues in your vehicle. It is a crucial part of the Audi's transmission because it communicates to the ECU about how fast or slow the car's crankshaft is turning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 via a grey wire. The ECU utilizes this signal to control fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. You can also 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. It should show around 1000 ohms of resistance between those two pins. This is a typical part across the Audi 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.