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 at the edge of transmission just above the flywheel gear. It sends a signal to the ECU via the grey wire (T55/49) which is then sent 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 G28 Engine Speed Sensor sends a signal to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer in the instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors according to the situation.

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

Testing can be a bit difficult since there are two connector pins, and they perform different functions but the best way to test it is by measuring resistance between the sensor and the ECU. If 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 as if the engine had run out of gas. Or, my injectors were not firing. This morning i pull out the spark plugs, three were soaked with gazoline and the 4th one was dry. When I crank the engine, there are no sparks, I put a piece of tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th one stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. I'm assuming the issue is elsewhere.

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

I'm not sure what to do. I believe that I've all other possibilities out. But i am afraid I might have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 gets a signal from the RPM sensor. The GM-style sender is the same as the G4 and both are used in the 80 100, 200, UrS and RS2 cars so you can easily find one at a junkyard or from a parts store. It is easy to test them - simply put your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that has to know the position and speed of the crankshaft in order to make decisions regarding timing of the fuel read more injectors, etc. In order to do this it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could cause the engine shutting down.

Some of the symptoms of a failing G28 sensor include an here inaccurate rev counter in the gearbox the gears are shifting faster than normal and/or a misfire when you are in gear. If you are experiencing any of these issues it is likely that your sensor is deteriorating and needs replacing. The good thing is that they are very cheap and easily accessible particularly if you're looking at a Bosch sensor, which is what ours are. You can also choose the GM version of this part is also a great option.

5. Tachometer

A faulty engine speed sensor could be the cause of get more info a slew of problems in your car. It's an essential component of the transmission in your Audi because it relays information to the ECU regarding how fast or slow the engine is turning. 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 the transmission, over the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU uses this signal to regulate the flow of fuel and boost and also timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection via pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms in these areas. This is the same across the Audi 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 them in wrecking yards.