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 near the edges of the transmission above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the outside of the transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indicator to the G5 Tachometer in instrument cluster.

The sensor is used to correlate 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 in the right way.

If this sensor fails when it fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in sync with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).

Testing can be a bit difficult since there are two pins for the connector 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 fully functional, it should read approximately 1000 ohms. If you are having problems with this component, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive decrease in power. It was as if the engine was running out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning, three were drenched in gasoline and the 4th was dry. I put tissue over each injector hole, and when I turn the engine on without sparks, the 3 with gazoline jump right out. The 4th one stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero ohm. So i assume the how to open audi car key problem is somewhere else.

I also tried to reset PID without success. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However the intermittent misfire issue audi a5 replacement key continues to occur at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows temperatures of -49c. Also, i noticed that the 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 feel like get more info i've pretty much all other possibilities out. I'm afraid i may have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sensor is the same as the G4 and both function in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or in replacement key for audi a3 a local parts store. It is simple to test them: simply 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 should be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, 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 sensors, the diagnostic scanner will show codes that could cause an engine shutdown.

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

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 car's engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.

The G5 engine sensor is located near the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The more info ECU utilizes this signal to regulate the amount of fuel and boost, and also timig. It also sends it to the G5 Tachometer inside the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Also, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. You should see the resistance to be around 1000 ohms between these points. This is the same across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU, so you might find good ones in wrecking yards.