How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

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

The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors accordingly.

If this sensor fails the ECU will show an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).

Testing can be a bit difficult since there are two pins for the connector and they perform different functions however the best method of testing it is to measure resistance between the sensor and the ECU. If the sensor is functional, it should read around 1000 ohms. Check for signs of coolant or oil in the connector bay if you have issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs. Three were soaked with gazoline and the 4th one was dry. When i crank the engine with no sparks, i place a tissue on the top of each of the injector holes and the 3 drenched with gazoline leap out, however the 4th stay closed. I tested the ground connection of ECU pins 14,30, and 48/55. I found zero ohm. I assume that the problem is elsewhere.

I also tried to reset the PID but with no luck. The car is able to start when the G28 is disconnected and is running fine when it is connected however it is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature of that is -49c even after unplugging it. I also noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, i feel i have pretty much completely ruled out all other possibilities. But i'm worried that I might have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find the spare in a salvage shop or parts store. Testing them is easy to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They must be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know both the position and speed the crankshaft to make decisions regarding fuel injector timing, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor get more info G28 to accomplish this. If you encounter a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger the engine shutting down.

Some of the signs of a malfunctioning G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or misfiring when in gear. If you have any of these issues it is likely your sensor is failing and should be replaced. They are cheap and easy-to-find especially if they're an Bosch model like ours. Alternatively, GM's version audi advanced key of this part is an option.

5. Tachometer

A malfunctioning engine speed sensor could be the reason behind numerous issues in your vehicle. It is an important part of the transmission of your Audi since it sends information to the ECU about how fast or slowly the engine is turning. This sensor could cause the audi a1 key transmission to fail 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 transmits an electrical signal through gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate fuel and boost, and also audi a4 spare key to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can test for sensor website failure by checking continuity from the sensor to the tachometer. Also, 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 as well as pin T26a/12. You should see the resistance to be around 1000 ohms between these points. This is a common part that is found across the Audi 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.