A Look At The Ugly Reality About Audi G28

How to Replace an Audi smart key replacement G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the top of the transmission just above the flywheel ring gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

Located on the edge of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 via a grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 Tachometer in instrument cluster.

The sensor is used to connect with the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also where the camshaft lies so that it can activate the spark and injectors.

If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are not in sync and possibly indicating the chain stretching or a jump link on the upper timing chain. The code won't appear without the additional information supplied by other sensors (G4 or G40).

It's a bit tricky to test since there are various connector pins, and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. It should read about 1000 ohms if the sensor is in full operation. Check for signs of coolant, or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive drop in power. It was like the engine had run out of gas. Or my injectors were not firing. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the 4th was dry. When I crank the engine without sparks, I put a piece of 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 New audi keys 48/55. I got zero ohm. I'm assuming the issue is in another place.

I also tried to reset the PID but without success. The car can start when the G28 is not plugged in and it runs perfectly when it is plugged in but it still has the intermittent misfire issue 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 is showing 2 bar when the actual pressure is 0.0 when i rev the engine.

I'm audi tt key fob not working sure what to do. I believe that I've ruled everything else out. I'm afraid 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 sensor is identical to the G4 and they both work in the 80, 100, 200, Audi Tt Replacement Key UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is easy 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 end facing upwards). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will show codes that could lead to an engine shutdown.

Some of the symptoms of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. It is probable that your sensor is failing and needs to be replaced if you experience any of these signs. They're cheap and easy to find particularly if they're a Bosch unit like ours. Alternately, GM's version this part would be an excellent choice.

5. Tachometer

A faulty engine speed sensor could be a cause for a slew of problems in your vehicle. It's an essential component of the transmission in your audi replacement key cost, as it transmits information to the ECU on how fast or slowly the engine of the car is turning. If this sensor fails, it could cause problems for the transmission and the other car's components.

The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49 through an uncolored wire. The ECU then processes this signal to regulate fuel, timig, and boost and then sends it on to the G5 Tachometer located in the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]) and between pin T6a/1 as well as pin T26a/12. You should see around 1000 ohms of resistance between those points. This is a typical component across the audi car key 80, 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good ones could be available in wrecking yards.