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. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, directly above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to regulate fuel and boost. It also sends signals to the G5 tachometer inside the instrument cluster.

The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can start spark and injectors accordingly.

If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of a chain stretch or a jump in the chain link of the upper chain. However the code will not appear 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 resistance between the sensor and the ECU. When the sensor is fully functional, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday accelerating full speed from highway paytoll i had an abrupt drop in power like the engine is running out of gas or the injectors aren't firing any more. Today, i pulled out the spark plugs, 3 were soaked with gazoline and the fourth was dry. I put tissue over each injector hole and when I start the engine without sparks, the 3 that have gazoline pop right out. The fourth one remains closed. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero Ohm. I'm assuming the issue is somewhere else.

I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it runs fine with the G28 connected. However, the intermittent misfire problem continues to occur at higher RPM. The temperature sensor for coolant (G62) shows the wrong temp value that is -49c even after unplugging it. Also, i noticed that the advanced key audi oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 if i crank up the engine.

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

3. Fuel Pump

The fuel pump in the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find a spare in a wrecking shop or a parts replacement audi key 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 at the connector end facing up). They must be infinite Ohms.

4. lost audi key ECU

The ECU in our 20vt turbo (3B AAN ABY) engines needs to know both the speed and position of the crankshaft in order to make a decision about timing of fuel injectors, etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If audi spare key replacement either of these goes wrong, you will receive codes on the diagnostic scanner which can cause the engine to shut down.

The signs of a malfunctioning G28 sensor include an inaccurate rev counter for the gearbox the gears are shifting faster than normal, and/or a misfire when you are in gear. If you have any of these issues, it is most likely that your sensor is failing and requires replacement. They click here are cheap and easy-to-find especially when they're a Bosch unit like ours. Alternatively, the GM version of this part is also a good choice.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of many problems in your vehicle. It's an essential component of the transmission of your Audi because it relays information to the ECU regarding how fast or slowly the engine is spinning. This sensor can cause the transmission to malfunction and other components in the car to be affected.

The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear. It sends a signal to the ECU at pin T55/49 through an uncolored wire. The ECU utilizes this signal to control the amount of fuel and boost, and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be the resistance to be around 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du, so you might find them in wrecking yards.