Audi G28 10 Things I d Loved To Know Sooner

How to Replace an replacement audi a3 key G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located on the outside of the transmission over the flywheel gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to regulate the amount of fuel and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft reached TDC, and the position of the camshaft, to trigger the spark and injectors.

If this sensor fails when it fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumped chain link in the upper timing chain. The code won't show without the additional information supplied by other sensors (G4 or G40).

It's a bit tricky to test as there are various connector pins, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. If the sensor is functional, it should read around 1000 ohms. If you're experiencing issues with this component, look for evidence of oil or audi tt Key Case coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive decrease in power. It was as if the engine had run out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were drenched in gazoline, the fourth one was dry. I put a piece of tissue over each injector hole, and when i start the engine with no sparks, the 3 with gazoline jump out. The 4th one stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I think the issue is somewhere else.

I also tried to reset PID but without success. The car can start when the G28 is disconnected and it runs perfectly when it is plugged in, but still has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. Also, i noticed that the gauge for oil pressure in the cockpit is showing 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 pretty much ruled out everything else. I'm concerned that i may have missed something. If anyone has any suggestions, please share them! 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 an extra in a wrecking shop or a parts store. Test them out to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the position and speed of the crankshaft to determine 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 wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.

A failing G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or an unfire when in the gear. If you have any of these issues it is likely your sensor is going bad and requires replacement. The good thing is that they are very affordable and easy to find, especially in the case of an Bosch unit which is what we have. Alternatively, GM's version of this part would be an excellent choice.

5. Tachometer

A damaged engine sensor could cause a number of problems within your vehicle. It's an essential component of the audi key replacement's transmission because it communicates to the ECU about how fast or slow the vehicle's crankshaft is spinning. When this sensor fails, it could cause problems for the transmission, as well as the other car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost as well as timig. It also transmits it to the G5 Tachometer in 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 as well as pin T26a/12. You should observe approximately 1000 ohms of resistance between those points. This is the same across the key audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 Du You may also find them in wrecking yards.