How to Replace an replacement audi Key cost G28 Engine Speed Sensor

Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. The sensor is situated near the edges of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends signals to the G5 Tachometer located in the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft reached TDC, and the location of the camshaft so that it can activate the spark and injectors.

If this sensor fails, the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain is stretched or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

It can be a bit difficult to test since there are various pins on the connector, and each one has different functions. The best way to do it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms when it is at full operation. Look for signs of coolant or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll, I experienced a big cut in power like the engine is running out of gas or injectors are not firing anymore. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth was dry. I put a piece of tissue over each injector hole, and when i turn the engine on without sparks, the three with gazoline jump right out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. Therefore, i think the issue is elsewhere.

I also tried to reset PID but without success. The car will start when the G28 is unplugged and runs fine when it is connected but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when unplugged, still 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 certain what to do, i feel i have pretty much completely ruled out all other possibilities. However, i'm afraid that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style sensor is identical to 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 at a parts store. It is simple to test them - just 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 must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the speed and position of the crankshaft in order to make decisions regarding timing of the fuel injectors, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you encounter a problem with either of these, the diagnostic scanner will show codes that could lead to the engine shutting down.

Some of the signs of a malfunctioning G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal and/or misfiring when in gear. If you are experiencing any of these issues it is likely your sensor is going bad and needs replacing. The good news is that they are very affordable and readily available, especially when you're looking at the Bosch model, which is what we have. Alternately, GM's version this part is an excellent choice.

5. Tachometer

A faulty engine speed sensor could be the cause of numerous issues with your car. It's a crucial component of the transmission in your Audi because it relays information to the ECU regarding how fast or slowly the car's engine is spinning. This sensor can cause the transmission to malfunction and other components of the car to be affected.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits an electrical signal through gray wire to ECU pin T55/49. The ECU uses this signal to regulate fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer located in the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a common component 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 so good ones could be available in wrecking yards.