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 situated near the edges of the transmission above the flywheel ring gear. It transmits a signal the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the outside of the transmission, above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends a signal 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 has to know when the crankshaft reached TDC, and where the camshaft lies in order to activate the spark and injectors.

If this sensor fails the ECU will throw the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain is stretched or a jump link on the upper chain of timing. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult because there are two connector pins, and they perform different functions however the best method of testing it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should read 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 accelerating full speed from highway paytoll, I experienced a big cut in power like the engine is running out of gas or the injectors aren't firing at all. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. When I start the engine with no sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline jump out but the 4th stays closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. I assume that the problem is somewhere else.

I also tried to reset the PID but without success. The car is able to start if the G28 is not plugged in and is running fine when it is plugged in but it still is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when 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. However, i'm afraid that i might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts store. It is easy to test them - simply put your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They should be infinite Ohms.

4. ECU



The ECU of our 20vt turbo (3B AAN ABY) engines must know the position and speed the crankshaft to make decisions regarding timing of fuel injectors, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner which could cause engine shut down.

A failing G28 sensor can cause an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, or a misfire in gear. It is likely that your sensor is failing and needs to be replaced if you notice any of these symptoms. The good news is that they are very affordable and easily accessible particularly if you're looking at the Bosch unit which is what we have. Alternately, the GM version of this unit is also a good option.

5. Tachometer

A failing engine sensor could cause a number of problems in your car. https://cameradb.review/wiki/So_Youve_Purchased_Audi_Advanced_Key_Now_What 's a vital component of your Audi's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is rotating. If this sensor fails, it can disrupt the performance of the transmission and the other car's components.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU then processes this signal to regulate the flow of fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those points. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 DU You may also find them in wrecking yards.