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Audi G28: The Ugly Reality About Audi G28
How to Replace an Audi G28 Engine Speed Sensor

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

1. Engine Speed Sensor

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

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

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

Testing is a bit tricky since there are two connector pins, and they have different functions but the best method to test it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is at full operation. Check for advanced key audi of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when accelerating from 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 weren't firing. I took out the spark plugs this morning, 3 were soaked with gasoline and the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero ohm. I'm assuming that the issue is in another location.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected, but it works fine when the G28 connected. However the intermittent misfire issue continues to occur at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I feel like i've pretty much ruled everything else out. But i'm worried that i might have missed something. Please let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal 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 locate a spare in a wrecking shop or a parts store. It is simple to test them - simply switch your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, for example. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.

A failing G28 sensor could result in an inaccurate speed counter for your gearbox and a gearbox which shifts more quickly than normal, or an unfire when in the gear. If you have any of these problems, it is likely your sensor is going bad and should be replaced. The good news is they are very cheap and easily accessible particularly when you're looking at a Bosch model, which is what ours are. If you prefer, GM's version of this component is an option.


5. Tachometer

A malfunctioning engine sensor can cause a variety of issues in your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU on how fast or slow the engine is turning. This sensor could cause the transmission to fail and other car components to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends signals via a gray wire to the ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can check for sensor failure by checking 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. It should show approximately 1000 ohms resistance between these two points. This is a common component across the Audi 80, 100 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.

Read More: https://www.g28carkeys.co.uk/audi-car-key-replacements-near-me/