How to replace audi key fob an audi q5 key G28 Engine Speed Sensor

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

1. Engine Speed Sensor

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

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu needs to 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 when it fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of sync with the Intake Camshaft. It could also indicate an issue with the chain or a jumped chain link in the upper timing chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

Testing is a bit tricky as there are two different connector pins and they serve different purposes but the best method of testing it is by measuring resistance between the sensor and the ECU. When the sensor is functional, it should read approximately 1000 ohms. Check for evidence of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed, i noticed a huge decrease in power. It was as if the engine was running out of gas. Or my injectors weren't firing. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was unclean. I put tissue over each injector hole and audi Key fob replacement when I start the engine without sparks, the ones with gazoline jump right out. The 4th one remains shut. I checked the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. I'm assuming that the issue is somewhere else.

I also tried to reset the PID but with no luck. The car is able to start when the G28 is not plugged in and runs fine when it is connected, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.

I'm not sure what to do. I feel like i've pretty much eliminated everything else. I'm afraid i may have missed something. Please let me know If you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is identical to 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 from a parts store. It is easy to test them: simply put your DMM into resistance mode and determine the distance between pins 1 and 2 (with the bump at the connector's 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 needs to know the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go wrong, you will receive codes on the diagnostic scanner which can lead to engine shutdown.

Some of the signs of a failing G28 sensor are an inaccurate rev counter for the gearbox the gears are shifting faster than normal and/or a misfire when in gear. If you are experiencing any of these issues it is likely your sensor is failing and requires replacement. They're cheap and easy to find particularly in the case of an Bosch unit like ours. Alternately, GM's version this part would be an option.

5. Tachometer

A faulty engine speed sensor could be the reason behind numerous problems in your car. It's a vital component of the audi remote key's transmission as it sends information to the ECU about how fast or slow the car's crankshaft 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 speed sensor is located at the outside of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU then uses and processes this signal to regulate fuel, timig and boost and then transmitting it to the G5 tachometer in the instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, 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 pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a typical component across the audi tt key case 80 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU, so the best ones might be availble in wrecking yards.