How to Replace an audi key programming G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the outside of the transmission just above the flywheel gear. It sends a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

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

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can start spark and injectors in the right way.

If this sensor fails when it fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumped 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's a bit tricky to test since there are various pins on the connector, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. When the sensor is functional, it should read approximately 1000 ohms. If you're experiencing issues with this part, check for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, i experienced an abrupt drop in power as if the engine was running out of gas or the injectors aren't firing at all. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth was dry. I put tissue over each hole in the injector and when i start the engine with no sparks, the three with gazoline jump right out. The fourth one remains closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I assume that the problem is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it is running fine with the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 when I crank up the engine.

I'm not sure what to do. I believe that I've ruled everything else out. But i'm worried that i might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sender is the same as the G4 and both function in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a salvage yard or from 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 at the connector's end facing up). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the speed and position of the crankshaft to determine timing of fuel injectors, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you encounter a problem with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.

The signs 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. It is likely that your sensor is failing and requires to be replaced if you experience any of these signs. The good news is that they are very cheap and readily available, especially if you're looking at an Bosch model, which is what we have. Alternately, GM's version this part is an option.

5. Tachometer

A failing engine sensor could cause a number of problems within your vehicle. It is a crucial part of your replacement audi keys's transmission, because it communicates to the ECU about how fast or slow the vehicle's crankshaft is rotating. This sensor could cause the transmission to fail and other components in the audi car key case to be affected.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the 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 [79]), and between pin T6a/1 as well as pin T26a/12. You should observe approximately 1000 ohms of resistance between those two pins. This is a standard part across the replacement audi A3 Key 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.