How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches 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 the grey wire (T55/49) and then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends an indication 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 must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger 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 out of sync with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumped chain link in the upper chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit tricky since there are two connector pins and they serve different purposes but the best way to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when the sensor is at full operation. If you're experiencing issues with this sensor, look for evidence of oil or coolant 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 as if the engine was running out of gas. Or my injectors weren't firing. This morning i pull out the spark plugs. Three were drenched in gazoline, the fourth was dry. When i crank the engine, there are no sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th one stays shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming the issue is elsewhere.

I also tried to reset PID without success. The car is able to start if the G28 is unplugged and is running fine when it is connected but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when it is unplugged, shows an ice temperature of -49c. Also i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure audi replacement car keys is 0.0 when I crank up the engine.

I'm not sure what to do. I think I've ruled everything else out. But i'm worried that I might have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style transmitter 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 salvage yard or in a local parts check here store. It is easy to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing up). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make a decision about fuel injector timing etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could lead to the engine shutting down.

A damaged G28 sensor could cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, and/or a misfire while in gear. If you have any of these issues it is likely that your sensor is failing and requires replacement. The good news is that they are quite affordable and easily accessible, especially when you're looking at an Bosch unit which is what ours are. Alternatively, the GM version of this component 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 Audi's transmission since it relays information to the ECU about how the car's crankshaft is rotating. If the sensor fails, it could cause problems for the transmission, as well as the rest of the car's components.

The G5 engine speed sensor is situated on the outside of the transmission, above audi a4 spare key the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via more info an uncolored wire. The ECU then processes this signal to regulate fuel, timig and boost, and also sends it on to the G5 tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. There should be the resistance to be around 1000 ohms between these points. 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 audi replacement key uk 1995 RS2 DU So, you may find some good ones in wrecking yards.