How to Replace an audi advance key G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located on the edge of the transmission above the flywheel ring gear. It transmits a signal to the ECU via the grey wire T55/49 and then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using the grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor is used to correlate the G40 Camshaft position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the location of the camshaft in order to activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate 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 is a bit challenging because there are two connector pins, and they have different functions however the best method to test it is by measuring resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is at full operation. If you're having issues with this part, check for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at a high speed I noticed a massive drop in power. It was like 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 4th one was dry. I put a piece of tissue over each hole in the injector and when I start the engine with no sparks, the three that have gazoline pop right out. The fourth one remains shut. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero Ohm. I'm assuming that the issue is in another location.

I also tried to reset PID without success. The car is able to start if the G28 is not plugged in and it runs perfectly when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. 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 crank up the engine.

I'm not certain what to do, but i believe that i've eliminated everything else. However, i'm afraid that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal sent from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or parts store. Testing them is easy - put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's side). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines must know both the speed and position of the crankshaft to determine timing of the fuel injector, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will display codes that could lead to an engine shutdown.

The signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal and/or a misfire when in gear. It is possible that your sensor is failing and needs to be replaced if you experience any of these symptoms. The good thing is that they are very affordable and easy to find particularly if you're looking at an Bosch model, which is what ours are. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine speed sensor could be the reason behind a slew of problems in your car. It's a vital component of your audi a1 key fob's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. If this sensor fails, it will disrupt the performance of the transmission, as well as the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. Also, you can check continuity between pin 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 a resistance of approximately 1000 ohms between these points. This is a common feature across the audi lost key tt audi a1 key case (visit the next post) 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU You may also find good ones in wrecking yards.