How to Replace an audi key copy G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows 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 the ECU via a grey wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the outside of the transmission, above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends an alert to the G5 Tachometer located in the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors accordingly.

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

Testing can be a bit difficult since there are two pins for the connector and replacement audi a4 key they perform different functions however the best method to test it is by measuring resistance between the sensor and the ECU. When the sensor is functional, replacement audi a4 key it should read about 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power like the engine is running out of gas or the injectors aren't firing anymore. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. I put a piece of tissue over each injector hole and when i turn the engine on without sparks, the 3 that have gazoline pop right out. The 4th one remains closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. So i assume the problem is elsewhere.

I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.

I'm not sure what to do, as i think i've pretty much ruled out everything else. I'm worried that i might have missed something. Let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 can be activated by a signal from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or from a parts store. It is simple to test them: simply switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed of the crankshaft to make decisions regarding fuel injector timing, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shut down.

The signs of a failing G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or a misfire when in gear. If you are experiencing any of these problems, it is likely your sensor is going bad and needs replacing. The good news is that they are quite affordable and easily accessible particularly in the case of a Bosch model, which is what we have. Alternately, the GM version of this component is also a great option.

5. Tachometer

A malfunctioning engine sensor can cause a number of problems in your car. It's a vital component of the Audi's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is spinning. This sensor can cause the transmission to fail and other components in the car to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to control the amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in 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 [79trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see the resistance to be around 1000 ohms in these areas. This is a common feature across the replacement audi a4 Key 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU So, you may find some good ones in wrecking yards.