Audi G28 10 Things I Wish I'd Known In The Past

How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located near the transmission's edge just above the flywheel gear. It transmits a signal to 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 located on the edge of transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then uses this information to control fuel, timig and boost. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors accordingly.

If this sensor fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).

Testing can be a bit difficult because there are two connector pins and they serve different purposes but the best method to test it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is in full operation. If you're experiencing issues with this component, look for signs 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 are not firing at all. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was unclean. I put a piece of tissue over each injector hole and when i turn the engine on without sparks, the three with gazoline jump out. The fourth one remains shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got 0ohm. So i assume the problem is somewhere else.

I also tried to reset PID without success. The car will start if the G28 is not plugged in and runs 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 temperatures of -49c. Also i noticed that the gauge for oil pressure in the get more info cockpit is showing 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, but i feel i have pretty much completely ruled out all other possibilities. I'm worried that i might have missed something. Let me know if you have any ideas! TIA!

3. read more Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style sender is the same as the G4 and both function in the website 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 put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the speed and position of the crankshaft to make decisions regarding fuel injector timing, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.

A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, or a misfire while in gear. If you experience any of these issues, it is likely your sensor is going bad and requires replacement. The good news is that they are quite affordable and readily available particularly if you're looking at a Bosch unit which is what we have. Alternatively, GM's version of this part would be a good option.

5. Tachometer

A failing engine sensor could cause a number of problems in your vehicle. It's an essential component of the Audi's transmission since it relays information to the ECU about how the car's crankshaft is spinning. This sensor could cause the transmission to malfunction and other components in the car to be affected.

The G5 engine sensor is located at the outskirts of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the 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 inside the instrument cluster. read more You can check for sensor failure by examining the continuity of the sensor to the tachometer. You can also examine the continuity between pins 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 detect the resistance to be around 1000 ohms in these areas. This is a typical component across the Audi 80 100, 200, UrS get more info and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.