The Most Prevalent Issues In Audi G28

How to Replace an audi a3 key G28 Engine Speed Sensor

Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located on the edge 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

The grey wire is situated on the outside of the transmission, above the flywheel ring. This sensor sends a signal via the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor is used to connect the G40 Camshaft position Sensor. The ecu must know 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 a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information provided by other sensors (G4 or G40).

It is a little tricky to test as there are several pins on the connector and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when the sensor is at full operation. Check for signs of coolant or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive reduction in power. It was like the engine was running out of gas. Or, my injectors were not firing. I pulled out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was unclean. When i crank the engine with no sparks, i place a tissue on the top of each of the injector holes, the 3 drenched with gazoline pop out, but the 4th stay closed. I checked the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. I'm assuming the issue is in another place.

I also tried to reset the PID with no success. The car will start if the G28 is disconnected and is running fine when it is plugged in but it still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even if it is not plugged in, shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do. I believe that I've all other possibilities out. However, i'm afraid that i might have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or 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 must be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines must know the speed and position of the crankshaft to make decisions regarding fuel injector timing, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these sensors go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

A malfunctioning G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, and/or a misfire while in gear. It is likely that the sensor audikey is failing and requires to be replaced if you notice any of these signs. The good news is they are very affordable and readily available particularly in the case of the Bosch model, which is what ours are. If you prefer, GM's version of this part would be a good option.

5. Tachometer

A faulty engine speed sensor could be a cause for numerous issues in your car. It is a crucial part of the audi a1 key fob's transmission since it relays information to the ECU about how fast or slow the vehicle's crankshaft is rotating. If the sensor fails, it could disrupt the performance of the transmission and the rest of the car's components.

The G5 engine speed sensor is located at the edge of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through a grey wire. The ECU utilizes this signal to regulate the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between those points. This is a common part across the audi a1 key replacement 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones could be available in wrecking yards.