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How to Replace an audi keyless entry G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located at the edge of transmission, above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 through the grey wire. The ECU utilizes this information to control the amount of fuel and boost. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is so it can trigger spark and injectors in the right way.

If this sensor fails the ECU will display 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 chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky because there are two connector pins and they have different functions but the best method to test it is to measure the resistance between the sensor and the ECU. When the sensor is operational, it should read approximately 1000 ohms. If you're experiencing issues with this component, look for signs of coolant or oil in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, 3 were drenched in gazoline, the fourth one was dry. When I start the engine without sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline leap out, however the 4th stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I think the issue is elsewhere.

I also tried to reset the PID without success. The car is able to start if the G28 is disconnected and is running fine when it is connected but it still has intermittent misfire issues at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temp value -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is 0.

I'm not certain what to do, as i think i've pretty much completely ruled out all other possibilities. But i am afraid i might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style transmitter 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 at a parts store. It is easy to test them - just switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know the position and speed the crankshaft in order to make a decision about fuel injector timing, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will show the codes that could trigger the engine shutting down.

A malfunctioning G28 sensor can cause an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, or a misfire while in the gear. It is possible that your sensor is failing and needs to be replaced if you encounter any of these symptoms. They're cheap and easy to find, especially if they're an Bosch sensor like ours. Alternatively, GM's version of this part would be a good option.

5. Tachometer

A failing engine speed sensor could be a cause for numerous issues in your vehicle. It's an essential component of the transmission in your audi car keys because it relays information to the ECU about how fast or slow the engine is turning. This sensor could cause the transmission to malfunction and other audi car key components to be affected.

The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to control the flow of fuel, timig and boost as well as sends it on to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by checking continuity from the sensor to the tachometer. Additionally, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should detect an average resistance of 1000 ohms between these two points. This is a common part that is found across the audi a5 key fob smart key replacement [click here to visit companyspage.com for free] 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good ones could be available in wrecking yards.