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 located near the edges of the transmission above the flywheel ring gear. It transmits a signal to the ECU through a grey wire T55/49, then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU then uses this information to control fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC and also the location of the camshaft so that it can activate 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, possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not appear on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult since there are two connector pins, and they have different functions but the best way to test it is by measuring resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is operating at its maximum. Look for signs of coolant, or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced an abrupt drop in power as if the engine was running out of gas or the injectors aren't firing any more. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was dry. I put tissue over each injector hole, and when i turn the engine on without sparks, the ones with gazoline jump out. The 4th one stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get zero Ohm. audi keys replacement I'm assuming the issue is somewhere else.

I also tried to reset the PID without success. The car can start when the G28 is unplugged and is running fine when it is plugged in but it still has intermittent misfire issues at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.

I'm not sure what to do. I feel like i've pretty much eliminated everything else. I'm afraid i may have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from audi tt keys the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. Testing them is easy by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on get more info the black read more end of the connector). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that needs to know the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. It uses a Crank Position Sensor read more G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.

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

5. Tachometer

A failing engine speed sensor could be a cause for a slew of issues with your car. It's an essential component of the transmission of your Audi because it relays information to the ECU regarding how fast or slowly the engine is turning. When this sensor fails, it could cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through gray wire to ECU pin T55/49. The ECU then processes this signal to control fuel, timig and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by checking 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 [79trace [79]) and between pin T6a/1 and pin T26a/12. You should observe approximately 1000 ohms of resistance between those two pins. This is the same across the Audi 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.