How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. The sensor is located on the outside of the transmission over the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49) and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, directly above the flywheel ring. The sensor transmits an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an indication to the G5 tachometer in the instrument cluster.

The sensor serves as a reference to correlate with the G40 Camshaft Position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors in the right way.

If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in 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 timing chain. The code will not appear without the additional information supplied by other sensors (G4 or G40).

Testing is a bit challenging since there are two connector pins, and they serve different purposes but the most effective method to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading around 1000 ohms. If you are having problems with this component, look for evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum 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 fourth was dry. I placed a tissue over each hole in the injector and when i start the engine without sparks, the three with gazoline jump out. The fourth one remains closed. I checked the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero Ohm. I assume that the problem is in another location.

I also tried to reset the PID without success. The car will start when the G28 is unplugged and is running fine when it is connected, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar while the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, i think i've pretty much ruled out everything else. However, i'm afraid that I might have missed something. If anyone has any ideas please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 audi key replacement near me is activated by a signal sent from the RPM sensor. The GM-style transmitter is similar to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. It is simple to test them - just put your DMM into resistance audi a1 key replacement mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that must be aware of the speed and position of the crankshaft in order to make a decision about timing of the fuel injectors, etc. To do this, it makes use of a Crank audi lost key Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can lead to engine shutdown.

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. It is possible that the sensor is failing and requires to be replaced if you notice any of these symptoms. The good news is that they are quite affordable and easily accessible particularly when you're looking at an Bosch sensor, which is what we have. Alternately, GM's version this component is website a good option.

5. Tachometer

A faulty engine speed sensor could be the reason behind many problems in your vehicle. It's a crucial component of the transmission in your Audi since it sends information to the ECU on how fast or slow the car's engine is turning. When this sensor fails, it could disrupt the performance of the transmission as well as the other car's components.

The G5 engine sensor is located at the edge of the transmission, just above the flywheel ring. It transmits a signal via an uncolored wire to the ECU pin T55/49. The ECU then processes this signal to control the flow of fuel, timig and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should see around 1000 ohms of resistance check here between those points. This is a standard 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. Good ones could be available in wrecking yards.