Why Nobody Cares About Audi G28

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 on the outside of the transmission over the flywheel gear. It sends a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer located in 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 signals to ECU pin T55/49 through the grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an alert to the G5 Tachometer within 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 trigger spark and injectors accordingly.

If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also be a sign of an issue with the chain or a jumpy chain link in the upper chain. The code won't appear without the additional information provided by other sensors (G4 or G40).

It's a bit tricky to test since there are various pins on the connector, and each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read about 1000 ohms when it is at full operation. Look for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at a high speed, i noticed a huge drop 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 start the engine without sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline pop out, but the 4th one stays closed. I tried to test the ground connections of ECU pins 14,30 and 48/55. I found zero ohm. Therefore, i think the issue is elsewhere.

I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it runs fine with the G28 connected. However, the intermittent misfire problem audi a5 replacement key persists at higher RPM. The coolant sensor (G62) even when it is unplugged, shows a audi replacement key uk temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is 0.

I'm not sure what to do, as i feel i have pretty much eliminated everything else. But i'm worried that I may have missed something. If anyone has any suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style transmitter 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 wrecking yard or at a parts store. It is easy to test them - simply switch your DMM into resistance mode and audi a1 keys determine the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines requires more info to know the speed and position of the crankshaft to make decisions regarding timing of fuel injectors, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If either of these go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.

Some of the signs of a failing G28 sensor are an 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. They're cheap and easy to find, especially if they're a Bosch unit like ours. Alternatively, the GM version of this part is also a good choice.

5. Tachometer

A failing engine sensor could cause a number of problems within your vehicle. It's a crucial component of the transmission in your Audi, as it transmits information to the ECU regarding how fast or slowly the car's engine is turning. When this sensor fails, it will cause problems for the transmission and the other car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can check the sensor for any failure by checking the 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 lost audi keys as between T6a/1, and the instrument cluster pin T26a/12. You should observe approximately 1000 ohms resistance between those points. This part is common across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS AN and the 1995 RS2 Du, so you might find them in wrecking yards.