How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal to the ECU via the grey wire (T55/49), then to the tachometer located in the instrument cluster.

1. Engine Speed Sensor

The grey wire is located on the edge of transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig 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 needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors in the right way.

If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jump in the chain link of the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

It's a bit tricky to test because there are several connector pins, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should read about 1000 ohms. Check for signs of coolant, or oil in the connector bay if you have issues with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at full speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. In the morning, i removed the spark plugs, 3 were soaked with gazoline and the 4th one was dry. I put tissue over each hole in the injector and when I turn the engine on without sparks, car Key replacement Audi the 3 with gazoline jump right out. The fourth one remains shut. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I get zero Ohm. I assume that the problem is somewhere else.

I also tried to reset the PID with no success. The car can start if the G28 is unplugged and runs fine when it is plugged in but it still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars while the actual pressure is 0.

I don't know what to do. I think I've eliminated everything else. I'm worried that i might have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. You can easily find an extra in a wrecking shop or a parts store. Testing them is easy to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft in order to make a decision about fuel injector timing etc. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go badly, you will see codes on the diagnostic scanner which could cause engine shut down.

Some of the symptoms of a failed G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when you are in gear. It is likely that the sensor is failing and requires to be replaced if you encounter any of these symptoms. The good news is they are quite affordable and easily accessible particularly when you're looking at the Bosch model, which is what ours are. Alternatively, the GM version of this part is also a good option.

5. Tachometer

A failing engine sensor could cause a variety of issues in your car. It's a crucial component of the transmission in your audi a4 key replacement because it relays information to the ECU regarding how fast or slowly the engine of the car is turning. If this sensor fails, it will disrupt the performance of the transmission as well as the other Car Key Replacement Audi's components.

The G5 engine speed sensor is situated on the edge of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to regulate the flow of fuel and boost and also to timigrate. It also sends it to the G5 Tachometer located in the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Also, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and car key replacement audi pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is a common feature across the Audi 80-100-200-RS2 range, beginning with the 1985 MC and up to the 1997 UrS AN and 1995 RS2 DU So, you may find good ones in wrecking yards.