How to Replace an audi a3 key fob Replacement G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is situated at the edge of transmission over the flywheel gear. It sends a signal to the ECU via 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 an uncolored wire. The ECU uses this information to control fuel and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the location of the camshaft so that it can activate the spark and injectors.

If this sensor fails, the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft aren't in sync and could indicate the chain is stretched or a jump link on 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 as there are various connector pins, and each has its own functions. The best way to do it is by measuring the resistance between the ECU and the sensor. When the sensor is fully operational, it should be reading around 1000 ohms. Look for signs of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced massive power loss as if the engine was running out of gas or injectors are not firing anymore. I took out the spark plugs this morning, three were soaked with gasoline and the fourth was dry. When I crank the engine with no sparks, I put a piece of tissue on top of each injector hole, the 3 drenched with gazoline pop out, but the 4th stays shut. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I'm assuming the issue is in another place.

I also tried to reset the PID without success. The car will start when the G28 is not plugged in and is running fine when it is plugged in but it still has the intermittent misfire issue 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 when the actual pressure is 0.0 when i rev the engine.

I don't know what to do. I think I've all other possibilities out. However, i'm afraid that I might have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is identical to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily locate a spare in a wrecking shop or a parts store. It is easy to test them: simply put 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

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that must know the speed and position of the crankshaft in order to make decisions about timing of the fuel injector, for example. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will show codes that could lead to the engine shutting down.

A damaged G28 sensor could cause an inaccurate speed counter for Cheap the gearbox, a gearbox that shifts more quickly than normal, or an unfire when in gear. If you have any of these issues, it is likely that your sensor is going bad and should be replaced. They are cheap and easy-to-find, especially when they're an Bosch model like ours. Alternately, the GM version of this component is also a good choice.

5. Tachometer

A damaged engine sensor could cause a variety of issues in your car. It's an essential component of the transmission in your replacement audi a3 key, as it transmits information to the ECU about how fast or slowly the car's engine is turning. If the sensor fails, it will disrupt the performance of the transmission and the rest of the car's components.

The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 via an uncolored wire. The ECU is then able to process the signal to control fuel, timig and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see a resistance of approximately 1000 ohms between these points. This part is common across the audi tt key programming 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find some good ones in wrecking yards.