The 10 Worst Audi G28 Failures Of All Time Could Have Been Avoided

How to Replace an audi key replacement cost 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, above the flywheel gear. It transmits a signal to the ECU through an uncolored wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, just above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 Tachometer in instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft has reached TDC, and the location 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 means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jumpy chain link in the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).

It is a little tricky to test because there are different pins on the connector and each has its own functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is in full operation. If you're having issues with this sensor, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or injectors aren't firing at all. Today, i pulled out the spark plugs. Three were drenched with gazoline the fourth one was dry. When i crank the engine, there are no sparks i put tissue on the top of each hole in the injector and the 3 that were drenched in gazoline pop out, but the 4th stay shut. I tried to test the ground connections of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming the issue is in another place.

I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. I also 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, as i feel i have pretty much completely ruled out all other possibilities. I'm concerned that i may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is similar to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare audi key in a wrecking shop or parts store. Test them out by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They must be infinite ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines needs to know both the speed and audikey position of the crankshaft in order to make a decision about timing of fuel injectors, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will display the codes that could trigger an engine shut down.

Some of the symptoms of a failed G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or misfiring when you are in gear. If you experience any of these issues it is likely your sensor is going bad and needs replacing. The good thing is that they are very cheap and readily available particularly if you're looking at an Bosch unit like ours. Alternately, the GM version of this component is also a good option.

5. Tachometer

A faulty engine speed sensor could be a cause for a slew of problems in your vehicle. It's a vital component of the audi key shell's transmission as it sends information to the ECU about how the car's crankshaft is turning. When this sensor fails, it will cause problems for the transmission as well as the rest of the car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU utilizes this signal to control fuel and boost, as well as timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check the sensor for Programmed any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is the same across the audi key programming 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du You may also find them in wrecking yards.