How to Replace an Audi A1 keys G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission over the flywheel 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

The sensor is located at the edge of the transmission, above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 through a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC and also where the camshaft lies to trigger the spark and injectors.

If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and could indicate the chain is stretched or a jump link on the upper chain of timing. The code will not appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit challenging as there are two different pins for the connector and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. It should read around 1000 ohms when the sensor is in full operation. If you're experiencing issues with this sensor, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday accelerating full speed from highway paytoll i had massive power loss like the engine is running out of gas or the injectors aren't firing anymore. I pulled out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was unclean. I put a piece of tissue over each injector hole, and when I start the engine with no sparks, the three that have gazoline pop right out. The fourth one remains shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I'm assuming that the issue is somewhere else.

I also tried to reset the PID without success. The car can start if the G28 is disconnected and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit is showing 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, but i think i've pretty much eliminated everything else. But i'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter is the same as the G4 and they both work in the 80, 100, 200, UrS and RS2 cars so you can easily find one at a salvage yard or from a parts store. It is simple to test them - simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know both the speed and position of the crankshaft to determine timing of fuel injectors, etc. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

The signs of a malfunctioning G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or a misfire when you're in gear. If you have any of these issues it is likely your sensor is going bad and should be replaced. They're inexpensive and easy to locate especially if they're an Bosch unit like ours. You can also choose the GM version of this component is also a good choice.

5. Tachometer

A failing engine sensor could cause a number of problems in your car. It is a crucial part of your audi tt key programming's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is spinning. If this sensor fails, it could affect the performance of the transmission and the other car's components.

The G5 engine sensor is located near the edge of transmission, above the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU uses this signal to control fuel and boost, and also to timigrate. It also sends it 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]) and between T6a/1 and the instrument cluster pin T26a/12. You should detect an average resistance of 1000 ohms in these areas. This is a standard part that is found across the Audi A3 Key Fob Replacement 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.