How to Replace an audi a1 car key 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 edge of the transmission, above the flywheel ring gear. It sends a message to the ECU through the grey wire T55/49 and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference point to connect 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, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on 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 perform different functions but the most effective way to test it is by measuring resistance between the sensor and the ECU. When the sensor is operational, it should read approximately 1000 ohms. If you are having problems with this part, check for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors are not firing at all. Today, i pulled out the spark plugs, three were drenched with gazoline the fourth was dry. I put a piece of tissue over each injector hole and when i start the engine without sparks, the 3 with gazoline jump out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30 and 48/55. I found 0ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID but without success. The car is able to start if the G28 is unplugged and is running fine when it is connected, but still is experiencing intermittent misfires 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 oil gauge in the cockpit shows 2 bars but the actual pressure is 0.

I'm not sure what to do, as i think i've pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sensor is the same as the G4 and they both work in the 80 100, audi a1 key replacement 200, UrS and RS2 cars so you can easily find one at a junkyard or at a parts store. It is easy 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 up). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to be aware of the position and speed of the crankshaft to determine fuel injector timing, etc. 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.

The signs of a failed G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or misfiring when in gear. It is probable that your sensor is failing and requires to be replaced if you experience any of these symptoms. They're inexpensive and audikey easy to locate especially when they're an Bosch unit like ours. Alternately, GM's version this component is an option.

5. Tachometer

A faulty engine speed sensor could be a cause for numerous issues with your car. It is a crucial part of the replacement audi key fob's transmission because it communicates to the ECU about how the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other components of the car to be affected.

The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to control the flow of fuel, timig and boost as well as sends it on to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by examining the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. You should see around 1000 ohms of resistance between those points. This is the same across the audi etron key 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 DU, so you might find good ones in wrecking yards.